UC-NRLF 


THE 


By  STEPHEN  CHRISTIE 


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LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


Class 


Stephen  Christie 


BOILER 


RULES  AND  TABLES 

used  in  the 
CONSTRUCTION,  TESTING 


AND  OPERATION  OF  STEAM 


BOILERS 


Rules  Comprehensive 


and  Exemplified 


PUBLICATION 


OP  THC 

UNIVERSITY 

OF 


GENERAL 


Copyright.  1908 

by 
STEPHEN  CHRISTIE 


PREFACE. 

THE   writer,   after   many   years   of  experience   in   connection 
with  boilers,  as  a  boiler  maker,  master  boiler  maker,  and 
boiler  inspector,  has,  in  his  vocation,  found  it  necessary  to 
use  rules,  tables  and   formulas  in  conjunction  with  his  work  and 
duties  and  has  profited  by  those  of  older  and  wider  experience  in  the 
craft  and,  having  had  ample  opportunity,  inclination  and  resource 
for   research   for   comprehensive,   concise   and   condensed   formulas 
and  rules  governing  his  daily  duties,  .has  compiled  this  work. 

The  author  does  not  claim  originality ;  it  is  the  intention  to  make 
the  subject  as  clear  as  possible,  to  make  it  a  pleasant  study  so  that  the 
layman  can  master  the  many  rules  that  may  seem  too  intricate  and 
attention  has  been  given  to  the  most  practical  part  of  estimating 
values  in  connection  with  steam  boiler  designing. 

Many  valuable  and  scientific  books  have  treated  the  subject  of 
steam  boilers  and  some  exhaustively  and  from  them  I  have  learned. 
I  have  quoted  from  those  authors'  fund  of  information  and  from 
personal  experience,  and  it  will  be  my  aim  to  make  this  compilation 
clear  and  free  from  any  technicalities  that  would  in  a  measure  con- 
fuse the  student  and  sincerely  hope  it  may  accomplish  the  mission 
intended,  to  interest  those  whose  duties,  labors  and  interests  are  in 
connection  with  the  steam  boiler. 

STEPHEN   CHRISTIE. 


1 95020 


CHAPTER  I. 

MATERIALS. 

It  has  been  stated  by  historians  that  Tubal  Cain  was  an  iron 
worker,  no  doubt  an  artificer  in  plow  shares  and  pruning  hooks,  but 
that  in  remote  antiquity,  when  metals  were  few  in  number  and 
knowledge  of  their  uses  limited,  and  it  is  doubtful  if  the  steam  boiler 
was  among  the  articles  made. 

Historians  record  the  nature  of  metals  during  those  early  ages  as 
gold,  silver,  brass,  iron,  tin  and  lead,  and  also  state  that  bronze  had 
been  in  use  before  iron,  thus  we  may  favor  doubt  about  boilers  of 
some  description  being  in  use  during  those  ages  of  antiquity. 

Aristotle  seems  to  be  the  earliest  authority  quoted  on  the  subject 
of  iron,  saying  "that  iron  was  purified  from  acoria  by  melting,  and 
after  repeated  treatments  by  melting  became  purified."  What  state 
of  purification  in  relation  to  iron  working  tools  or  metals  was  not 
stated. 

Daimachus,  an  early  writer  on  the.  subject  mentions  different 
kinds  of  steel  and  the  purposes  to  which  they  were  used,  and  sev- 
erally suited,  viz. : 

Chalybdie  for  carpenter  tools. 

Lacedoemonian  for  files  and  drills  and  stone  cutters'  tools. 

Lydian  for  knives  and  razors. 

Thus  ancient  history  records  some  notice  of  materials  used  in 
boiler  construction,  but  it  is  doubtful  if  ancient  process  of  manu- 
facturers or  knowledge  of  material  construction  brought  it  up  to 
anything  like  the  state  of  perfection  that  could  be  used  in  steam 
boilers  of  today. 

This  chapter  was  not  intended  to  treat  on  metallurgy  only  to 
touch  upon  materials  as  now  used  in  these  days  of  high  pressure 
boilers. 

Manufacturers  assume  great  responsibilities  in  selecting  material 
for  boilers,  hence  care  in  selection. 

Boiler  making  today  is  a  science,  demanding  scientific  education 
and  knowledge  gained  by  research,  investigation  and  reasoning. 

The  writer  can  go  back  mentally  to  the  days  when  boiler  making 
was  apparently  in  its  infancy,  this  when  comparing  the  boilers  of  to- 

5 


6  THE  BOILER. 

day  with  the  demands  for  power  and  when  the  very  low  pressures 
were  then  well  suited  to  the  low  grade  material  manufactured ;  de- 
signs crude,  seams  out  of  all  proportions,  bracing  out  of  reasoning, 
and  the  ignorant  mechanic,  whose  only  evidence  of  work  was  strong 
in  arm,  wrought  defects  without  thought  of  effects. 

There  is  evolution  and  revolution  in  boiler  making  today. 

High  pressures  are  necessary,  also  care  in  selecting"  materials  and 
designing  boilers.  The  construction  for  the  demands  today  are  high 
pressures  ;  due  to  competition,  economy  and  fuel  and  space.  It  is  nec- 
essary then  to  have  all  parts  equal  in  strength,  different  parts  favored 
with  material  of  specific  quality,  such  as  braces,  tubes,  fire  sheets, 
where  circulation  is  least ;  corrosion,  expansion,  contraction  or  pit- 
ting active  will  necessitate  increased  thickness  of  plate ;  again,  to 
secure  complete  circulation,  combustion  of  fuel,  etc. ;  to  arrange  heat- 
ing surface  in  proportion  to  grate  area  and  steam  space,  to  make  the 
form  of  boiler  such  that  it  can  be  constructed  without  mechanical 
difficulty  or  great  expense. 

Designs  must  be  made  to  give  strength,  durability  under  the 
action  of  hot  gases  and  corrosive  elements,  to  be  accessible,  for  clean- 
ing, repairing  and  to  provide  safety  appliance  of  ample  proportions 
and  applied  properly.  Thus  the  necessity  of  the  greater  education  in 
boiler  designing  and  construction  and  knowledge  of  material  used. 

Material  for  boiler  purposes  as  well  as  other  uses  invariably  con- 
tains in  combination  sonic  proportion  of  various  elements,  and 
although  these  may  appear  small,  have  very  marked  influence  upon 
its  strength,  ductility  and  working  qualities,  thus  making  it  neces- 
sary to  have  both  chemical  as  well  as  physical  tests.  In  the  manu- 
facturing of  boiler  material  the  process  of  carburization  changes  the 
nature  and  properties  of  contained  carbon,  thus  wrought  iron  con- 
tains from  5  per  cent  to  only  a  trace  per  cent  of  carbon,  and  steel 
including  all  kinds  of  iron  contains  not  more  than  1.75  per  cent 
of  carbon  and  varies  in  fusibility,  hardness,  susceptibility  to  temper- 
ing and  malleability.  The  first  two  properties  being  increased  by 
increase  of  carbon,  while  the  others  are  diminished. 

All  ores  go  through  the  process  of  reduction,  and  the  more  im- 
purities they  contain  the  greater  amount  of  work  is  necessary  to 
treat  them ;  these  include  carbonic  acid,  water,  combustible  and 
earthy  matter. 


MATERIAL.  7 

CAST  IRON. 

In  cast  iron  these  qualities  looked  for  are  taken  from  the  fuel  and 
mode  of  smelting",  this  materially  as  much  as  the  character  of  ore.  To 
convert  cast  iron  into  bar,  forged  or  malleable  iron,  it  has  to  be  re- 
fined by  smelting  with  coke  or  charcoal ;  this  process  eliminates  the 
oxygen  and  carbon  which  may  be  left,  thus  bringing  it  to  a  state  of 
refined  metal,  this  is  forged  under  hammer,  passed  through  roll  and 
drawn  into  bars,  cut  in  lengths  and  formed  into  bundles  or  piles,  again 
reheated  and  once  more  hammered  and  rolled  into  any  shape.  Cast 
iron  has  in  its  makeup  carbon-silicon ;  this  is  a  slag  and  its  presence 
makes  iron  and  steel  hard  and  brittle,  but  up  to  6  per  cent  is  harmless 
providing  3  per  cent,  of  manganese  is  present  with  it.  Manganese, 
of  which  5  per  cent  is  sufficient  to  make  iron  cold  short,  is  valuable 
in  iron  to  be  converted  into  steel. 

Sulphur  and  phosphorus,  when  8  per  cent  is  present,  make  iron 
and  steel  crystallized  and  unfits  it  for  plate  for  boiler  purposes. 

Arsenic  increases  the  hardness  in  steel  at  the  expense  of  tough- 
ness, as  does  carbon  with  it  in  form  of  graphite.  The  gray  iron  con- 
tains most  graphite  and  carbon,  making  it  more  fusible  and  softer 
than  white  iron.  The  latter  contains  more  combined  carbon  ;  these 
constituents  vary,  thus  having  various  influence  on  the  mechanical 
properties,  and,  after  repeated  fusings,  loses  its  carbon. 

THE  ELEMENTS  IN  CAST  IRON  ARE  AS  FOLLOWS: 


ELEMENTS.  PERCENTAGE. 

Combined  carbon 15  to  1 .  25  per  cent 

Graphite 1 .  85  to  3  . 25 

Silicon 15  to  5  . 

Sulphur 0    to     .05 

Phosphorus 0    to  1 .  3 

Manganese .  .  : 0    to  1 .  5 

Iron 90 .     to  95  . 

Cast  iron  is  not  reliable  for  boiler  construction  unless  for  very  low 
pressure,  while  it  resists  corrosion  it  is  brittle  and  to  get  strength 
great  thickness  is  necessary. 

From  cast  iron  to  steel,  plate  is  susceptible  to  the  widest  variation 
in  its  character ;  cast  iron  as  extracted  from  ore,  is  melted  with  com- 
parative facility  and  according  to  mode  of  operation  in  foundry,  may 
be  rendered  so  hard  that  it  requires  special  tools  to  work  it. 


8  THE  BOILER. 

This  metal  by  treatment  with  heat  and  air  is  converted  into  great 
tensile  strength  and  ductility,  still  soft  and  easily  worked  into  shapes 
without  fracture. 

The  difference  in  molecular  construction  between  cast  and  malle- 
able iron  is,  the  cast  iron  contains  a  larger  proportion  of  carbon  and 
some  silicon,  the  malleable  iron  practically  none — thus  to  produce 
steel  the  cast  iron  is  melted  first,  then  wrought  iron  and  steel  scraps 
are  added  by  degrees  (these  in  equal  proportion),  then  an  addition 
of  spiegeleisen  is  added  with  manganese ;  as  soon  as  this  metal  ceases 
to  flow  it  is  removed  and  poured  into  moulds,  reheated  and  rolled 
into  plate. 

WROUGHT  IRON. 

Wrought  iron  is  made  by  the  process  called  puddling  to  eliminate 
the  graphite  and  combined  carbon  from  the  pig  iron,  leaving  sufficient 
to  give  strength  in  this  new  combination.  In  operation  the  mass  is 
heated  and  kneaded  by  the  paddles  into  blooms,  and  these  are  com- 
pressed under  a  hammer  to  remove  the  slag,  again  heated,  rolled  out 
and  further  squeezed  by  passing  through  rolls,  thus  forming  a  puddle 
bar.  These  bars  are  broken  up  and  worked  by  hammering  and  roll- 
ing more  or  less  according  to  degree  of  purity  and  strength  required, 
thus  iron  plates  retain  the  fibrous  quality  imparted  to  the  bar,  but 
owing  to  the  secretion  of  cinder  scale  between  the  layers  (thus  pro- 
ducing.blisters),  careful  tests  are  necessary  by  eye  or  hammer. 

Wrought  iron,  while  possessing  great  tenacity  combined  with 
toughness  and  ductility  is  well  adapted  to  resist  sudden  strains. 

While  the  puddle  bars  are  going  through  the  rolls  oxide  of  iron 
is  formed  in  scales,  caused  by  the  hot  iron  coming  in  contact  with  the 
air;  these  scales  are  collected  for  the  puddling  furnace,  with  use 
being  that  of  absorbing  the  carbon  from  the  iron. 

The  wrought  iron  is  Lamina  in  its  construction,  is  ductile  and  has 
a  tensile  strength  varying  up  to  55,000  pounds  per  square  inch  and 
a  ductility  to  40  per  cent ;  its  uses  in  boiler  construction  are  in  tubes, 
rivets,  braces  and  for  reinforcement.  .One  objectional  feature  in 
iron  plates  is  the  smallness  of  plate  that  can  be  manufactured  with- 
out chance  of  blistering  or  lamination ;  another  is  the  excess  of  labor 
due  to  more  seams,  thus  reducing  the  strength  of  boiler. 

The  great  advantages  steel  has  over  wrought  iron  are,  plate  can 


MATERIAL.  9 

he  made  in  sizes  of  larger  dimensions,  boilers  can  be  made  of  lighter 
material,  greater  power  of  conductivity  of  heat  can  be  secured,  but  it 
necessitates  greater  care  in  flanging  the  material  and  in  fitting  up. 

MATERIAL. 

Average  crushing  and  breaking  strains  of  iron  and  steel : 

Breaking  strain  of  wrought  iron 23  tons 

Crushing  "     17 

Breaking  strain  of  cast  iron 7^ 

Crushing        "        "      "        "    50 

Breaking  strain  of  steel  bars 55 

Crushing        "        "      "        "       110 

this  per  square  inch  of  section. 

STEEL  PLATE. 

Steel  is  a  carburet  of  iron  and  the  earliest  invention  of  same  was 
prepared  by  fusion  and  not  by  cementation ;  in  this  later  process  the 
metal  is  surrounded  by  charcoal,  and  thus  it  draws  its  supply  of 
carbon,  the  molecules  of  iron  taking  up  the  latter. 

Since  that  early  process  there  have  been  several  methods  em- 
ployed to  produce  the  steel,  viz. : 

1st  Direct  from  ores. 

2nd  By  addition  of  carbon  and  malleable  iron. 

3rd  By  the  partial  decarburization  of  pig  iron. 

4th  By  diluting  the  carbon  in  pig  iron  and  the  addition  of  malleable  iron. 

Steel  plate  is  termed  mild  steel,  low  steel  and  high  steel,  which 
contains  a  high  percentage  of  carbon.  The  following  table  will  show 
the  proportion  of  carbon  and  corresponding  hardness : 


NO.    OF 
HARDNESS. 

PER  CENT   OF 
CARBON. 

OBSERVATION. 

1 
2 

3 

4 

1.58  to  1.38.  . 
1.38  to  1.12  
1.12  to     .88  
.88  to     .62  

.  .  .  cannot  be  welded. 
.  .  .welds  easily  and  used   for   chisels. 
.  .  .used  for  cutting  tools. 
.  .  .mild  steel  for  tires,  etc 

5 
6 

7 

.62  to     .38and\ 
.38  to     .15         / 

15  to      05 

/tempers  slightly,  steel  for  boiler 
\     plates, 
/does  not  temper,  used  for 
\     machinery 

Steel  and  iron,  like  all  other  metals,  are  composed  of  atoms 
grouped  in  molecules,  and  any  force  that  alters  the  relations  of  the 
atoms  in  the  molecules  modifies  the  physical  properties  of  the  metal, 
thus  in  heating,  cooling  and  crushing  the  physical  properties  of 
metals  vary  with  its  degree  of  purity. 


10  THE  BOILER. 

Density  of  a  metal  is  dependent  on  the  intimacy  of  the  contact 
between  the  molecules  and  is  influenced  by  temperature  and  rate  of 
cooling;  its  density  can  be  augmented  by  hammering  or  any  com- 
pressing stress ;  pressure  on  all  sides  increases  its  density. 

Malleability  is  the  property  of  permanently  extending  in  all 
directions  without  rupture  by  pressure  produced  by  slow  stress  or 
by  impact. 

Ductility  is  the  property  that  enables  metal  to  be  worked  into 
flanges  or  drawn  into  wire,  and  this  ductility  increases  with  increased 
temperature. 

Tenacity  is  a  property  possessed  by  metals  in  varying  degree, 
it  is  the  resisting,  the  separating  of  the  molecules  after  the  limit  of 
elasticity  has  passed. 

Hardness  is  the  resistance  offered  by  the  molecules  of  a  substance 
to  their  separation  by  penetrating  action  of  another  substance. 

Brittleness  is  the  sudden  interruption  of  molecules,  cohesion, 
when  substances  are  subjected  to  the  action  of  some  extraneous 
force,  such  as  a  blow  or  change  of  temperature  and  largely  influ- 
enced by  purity  of  metal. 

Elasticity  is  the  power  a  body  possesses  of  resuming  its  original 
form  after  removal  of  an  external  force  which  has  changed  its 
form,  and  to  measure  the  strength  of  metals  it  is  necessary  to  deter- 
mine : 

First. — The  greatest  stress  the  metal  can  sustain  within  the  limits 
of  elasticity. 

Second. — The  total  exent  of  strain  before  rupture  takes  place. 

Third. — The  ultimate  tensile  strength  or  maximum  stress  the 
metals  can  sustain  without  rupture. 

The  difference  between  steel  and  iron  is  seen  when  subjected  to 
a  high  temperature  and  suddenly  cooled  by  plunging  in  cold  water. 
The  iron  is  affected  very  little  while  the  steel  becomes  hardened. 

A  chemical  test  to  distinguish  iron  from  steel  is  by  placing  a  drop 
of  diluted  nitric  acid  upon  a  clean  surface  of  the  metal ;  a  greenish- 
gray  stain  appears  upon  iron ;  on  the  steel  a  black  spot,  this  latter  is 
due  to  the  separation  of  carbon. 

The  processes  of  making  boiler  plate  are  the  Siemens-Martin  or 
open  hearth  process,  and  by  the  Bessemer  converter.  The  latter  is 
costly.  The  former  offers  better  facilities  for  testing  the  quality 


MATERIAL. 


11 


while  still  in  a  molten  state  and  its  character  modified  at  will  by  addi- 
tion of  such  material  required  to  produce  desired  results.  While  the 
Bessemer  process  is  not  as  desirable  owing  to  its  not  offering  facil- 
ities for  testing  or  adjustment.  The  elements  that  increase  tensile 
strength  will  reduce  ductility,  as  carbon  increases  strength  up  to  a 
certain  limit  then  beyond  excess  reduces  it,  as  a  certain  limit  separ- 
ates steel  from  cast  iron. 

The  hardening  elements  are  carbon,  silicon,  manganese  and  phos- 
phorus. 

Manganese  steel  contains  a  high  percentage  of  the  latter,  having 
a  little  carbon  and  is  avoided  in  boiler  construction. 

The  qualities  in  steel  for  boilers  are  homogenity,  tenacity,  elas- 
ticity and  ductility  ;  distinct  from  steel  used  for  other  purposes  boiler 
plate  should  be  tcugh  and  not  of  such  a  character  that  it  might 
harden  under  the  action  of  sudden  great  changes  of  temperature. 

Steel  is  structural  and  chemical,  it  is  a  compound  or  an  alloy  of 
elements,  silver,  tungsten,  chromium,  titanium,  silicon  and  cyanogen. 
It  forms  an  intermediate  link  between  ordinary  cast  iron  and 
wrought  iron,  uniting  with  the  properties,  of  both  and  its  distin- 
guishness  or  characteristic  is  its  capability  of  being  hardened  or 
softened  by  rapid  or  slow  cooling. 

TABLE  SHOWING  COMPARISONS  OF  IRON  AND  STEEL: 


IRON 


STEEL. 


SWEDISH. 

PENN. 

MILD. 

VERY   MILD. 

Carbon  
Silicon  
Sulphur  
Phosphorus  
Manganese  
Iron.  

.087 
.56 
.005 



99  '220 

.067 
.020 
.001 
.075 
.009 
99.828 

.238 
.105 
.012 
.034 
.184 
99.427 

.009 
.163 
.009 
.084 
.620 
99.115 

U.  S.  GOVERNMENT  SPECIFICATIONS  FOR  MATERIAL. 

Fire-box  steel  should  show  a  tensile  strength  of  not  less  than 
52,000  pounds,  and  not  over  62,000  pounds  per  square  inch,  an 
elastic  limit  not  less  than  one-half  (l/2)  the  ultimate  strength,  elon- 
gation 25  per  cent  and  tested  as  follows:  Cold  and  quench  bends 


12  THE  BOILER. 

180  degrees  flat  on  itself  without  fracture  on  outside  of  bent  portion, 
not  over  .04  per  cent  of  sulphur  or  .04  per  cent  phosphorus. 

Flange  steel  to  show  a  tensile  strength  of  from  55,000  to  65,000 
pounds  per  square  inch,  elastic  limit  not  less  than  one-half  of  its 
ultimate  strength,  elongation  25  per  cent,  cold  and  quench  bends  180 
degrees  flat  on  itself,  without  fracture  on  one  side  of  bent  portion 
and  not  over  .04  per  cent  of  phosphorus  and  not  over  .05  per  cent 
of  sulphur. 

Extra  soft  steel  to  show  a  tensile  strength  of,  45,000  to  55,COO 
pounds  per  square  inch,  elastic  limit  not  less  than  one-half  its  ulti- 
mate strength,  elongation  28  per  cent,  cold  and  quench  bends  180 
degrees  flat  on  itself  without  fracture  on  outside  of  bent  portion,  not 
over  .04  per  cent  of  sulphur  or  phosphorus. 

Plates  and  steel  rivets  to  be  made  by  the  open  hearth  process  and 
tests  to  be  made  to  determine  tensile  strength,  ductility,  elasticity, 
elongation  ;  physical  and  chemical  tests  to  be  made  at  place  of  manu- 
facture, all  plates  to  be  plainly  stamped  at  corner  near  center.  Mate- 
rial for  stay  bolts  and  braces  to  have  a  tensile  strength  of  not  less 
than  46,000  pounds  per  square  inch  when  made  of  iron  and  not  less 
than  55,000  pounds  when  made  of  steel. 

Steel  rivet  material  to  have  a  tensile  strength  of  50,000  to  60,000 
pounds  per  square  inch  of  sectional  area  and  elastic  limit  not  less 
than  one-half  the  ultimate  strength,  a  bending  test  as  follows  at  180 
degrees  flat  on  itself  without  fracture  on  outside  portion ;  elonga- 
tion 26  per  cent. 

Iron  rivet  material  to  have  a  tensile  strength  of  40,000  pounds 
per  square  inch. 

SPECIFICATION  AND  TESTING  OF  MATERIALS. 

The  U.  S.  Government  rules  as  specified  for  the  construction  of 
boilers  coming  under  federal  supervision  are  as  follows : 

"That  iron  or  steel  plate  intended  for  construction  of  boiler  to  be 
used  in  steam  vessels  shall  be  stamped  in  at  least  five  different  places 
by  the  manufacturer  at  place  where  made,  viz.,  at  corners  about 
eight  inches  from  edges  and  near  center  and  with  number  of  pounds 
per  square  inch  of  tensile  strength ;  it  will  be  the  sectional  inch  and 
which  must  not  be  less  than  45,000  pounds  for  iron  or  50,000  pounds 


MATERIAL.  13 

for  steel ;  from  plates  shall  be  taken  coupons  and  prepared,  by  plain- 
ing edges,  these  test  pieces  shall  be  at  least  16  inches  in  length  and 
from  one  and  one-half  (1^)  inches  to  three  and  one-half  (3^) 
inches  in  width  at  ends,  which  ends  shall  join  by  an  easy  fillet,  a 
straight  in  the  center  of  at  least  9  inches  in  length  and  1  inch  in 
width,  in  form  to  the  following  diagram  marked  with  light  prick 
punch  marks  at  distances  one  inch  apart,  spaced  so  as  to  give  8 
inches  in  length." 


About  8  inches.     ). 


iMnchee. 


About  8  inches,     j. 


The  strain  necessary  to  break  the  test  pieces  as  described  is  taken 
the  proportion  of  the  T  S  (tensile  strength)  per  square  inch. 


EXAMPLES. 


Test  piece  or  coupon  reduced  to  smallest  part  is  one-fourth  of  a 
square  inch  and  is  broken  at  15,000  pounds. 

15000 

4 

60000  TS  per  square  inch 

To  determine  the  elongation,  the  part  cut  out  in  test  piece 
marked  at  inch  sections  and  the  force  necessary  to  break  it  asunder 
is  the  proportionate  part  of  the  T  S  per  square  inch,  and  distance 
stretched  represents  percentage  of  elongation. 

EXAMPLE. 

To  find  percentage  of  elongation  in  a  test  piece.  Coupon  8" 
before  testing,  elongated  to 


10.  5  =10^"  after  testing 
8      =  before  testing 

10 .  5)   2 .  500  (23  per  cent  of  elongation 
2  10 

400 
315 


85 


14  THE  BOILER. 

Test  piece  1    /8    x  ^  breaks  at  34,000  pounds. 

1.625 
.375 

8125 
11375 
4875 


.609375)34000.0000(55829  Ibs.  TS 
3045 


3550 
3045 

5050 

4872 

1780 
1218 


5620 
5481 

139 

Strain  necessary  to  break  a  test  piece  is  the  proportionate  part 
of  the  tensile  strength  per  square  inch. 

A  piece  of  plate  sectional  area  .5  square  inch  breaks  at  30,000 
pounds. 

.5000)30000.0000(60000  Ibs.  TS 
300000 


000 


TABLE. 

Showing  width  of  plate  expressed  in  100th  of  an  inch  that  will 
equal  one  quarter  of  one  square  inch  of  section  of  the  various  thick- 
ness of  plate. 

Example.  —  If  plate  is  y\  inch  in  thickness  the  width  should  be 
100th  of  an  inch  wide  to  equal  one  quarter  of  one  square  inch  of 
section  or  as  follows  : 


.21X119  .........................................  33X76 

.  23  X  109  .........................................  35X71 

MX100  ........................................    \  X67 

.26X    96  ................................  . 

.29X    86 


MATERIAL.  15 

Only  steel  plates  manufactured  by  what  is  known  as  the  basic  or 
acid  open  hearth  process  will  be  allowed  to  be  used  in  the  con- 
struction of  boilers  for  marine  purposes  and  manufacturer  shall 
furnish  a  certificate  with  each  order  of  steel  tested  stating  technical 
process  by  which  said  steel  was  manufactured,  this  is  not  intended 
to  apply  to  plates  used  in  construction  of  Bessemer  steel  tubes. 

No  plate  made  by  acid  process  shall  contain  more  than  0.06  per 

f  cent  of  phosphorus  or  0.04  per  cent  of  sulphur,  and  no  plate  made  by 

Jfche  basic  process  shall  contain  more  than  .04  per  cent  of  sulphur  or 

/phosphorus.    This  to  be  determined  by  analysis  by  the  manufacturer. 

Steel  plates  must  have  a  tensile"  strength  not  less  than  55,000 
pounds  and  not.  over  75,000  pounds  per  square  inch  of  section,  but 
boilers  whose  construction  is  commenced  after  June  30,  1905,  where 
plate  will  come  in  contact  with  fire  either  in  use  or  in  course  of  con- 
struction of  the  boiler  the  tensile  strength  shall  not  be  more  than 
70,000  pounds  per  square  inch  of  section. 

No  plate  shall  be  stamped  with  a  greater  tensile  strength  than 
70,000. 

Elongation  shall  show  at  least  25  per  cent  in  a  length  of  2  inches 
for  thickness  to  one-fourth  (*4  )  inclusive  in  a  length  of  4  inches  for 
over  one-fourth  to  seven-sixteenths  inch,  inclusive ;  in  a  length  of  6 
inches  for  all  plates  over  seven-sixteenths  inch.  The  sample  must 
show  a  reduction  of  sectional  area  as  follows : 

At  least  50  per  cent  for  thickness  over  one-half  to  three-fourths 
inch  inclusive,  45  per  cent  for  thickness  over  one-half  to  three- 
fourths  inclusive,  and  32.5  per  cent  for  thickness  over  three-fourths 
of  an  inch. 

Quenching  and  bending  test  pieces  shall  be  at  least  12  inches  in 
length  and  from  1  to  3j/2  inches  in  width.  The  sides  where  sheared 
or  planed  must  not  be  rounded,  but  the  edges  may  have  the  sharp- 
ness taken  off  with  a  fine  file.  The  test  piece  shall  be  heated  to  a 
cherry  red  (as  seen  in  a  dark  place)  and  then  plunged  into  water  at 
a  temperature  of  about  82  degrees  F.  Thus  prepared  the  sample 
shall  be  bent  to  a  curve,  the  inner  radius  of  which  is  not  greater  than 
one  and  one-half  times  the  thickness  of  the  sample  without  cracks 
or  flaws,  the  ends  must  be  parallel  after  bending. 

Iron  plates  when  tested  must  show  a  tensile  strength  of  not  less 
than  45,000  pounds  and  not  over  60,000  pounds  per  square  inch  of 


16  THE   BOILER. 

sectional  area  and  show  an  elongation  of  at  least  15  per  cent  in  a 
length  of  8  inches  and  a  reduction  of  area  as  follows :  For  plate 
having  45,000  T  S  15  per  cent,  and  for  each  additional  1,000  pounds 
up  to  55,000  add  1  per  cent ;  for  samples  over  55,000  pounds  up  to 
60,000  T  S  25  per  cent  shall  be  required ;  a  bending  test  as  follows  :  a 
piece  12  inches  in  length  and  from  1  to  3T/2  inches  in  width,  the  edge 
not  to  be  rounded,  then  bent  cold  to  an  angle  of  90  degrees  to  a  curve 
the  inner  radius  of  which  no  greater  than  one  and  one-half  times'  the 
thickness  of  the  sample  without  cracks  or  flaws." 

The  chemical  or  analytical  test  is  for  the  purpose  to  show  right 
proportions  of  elements  and  properties  useful  in  the  material's 
make-up,  for  specific  purposes,  and  if  free  from  those  whose  pres- 
ence are  bad,  a  certain  proportion  of  carbon  gives  it  a  given  degree 
of  strength,  while  a  small  percentage  of  sulphur  will  render  it  use- 
less for  boiler  purposes.  The  effect  of  the  latter  and  phosphorus  is 
crystalization  of  metal. 

Plates  are  usually  ordered  by  thickness,  but  there  are  occasions 
when  weight  is  defined  rather  than  the  thickness  and  rejected  unless 
up  to  demands.  The  effects  sometimes  are  that  owing  to  the  plates 
being  made  of  large  dimensions  and  cut  up  to  demands  for  smaller 
sizes  some  of  uneven  thickness  are  left ;  this  is  due  to  the  process  of 
rolling,  the  center  of  rolls  expanding,  thus  leaving  center  of  plate 
thicker ;  while  rolls  are  turned  in  center  to  obviate  this  effect  the 
heating  of  rolls  must  offset  the  turning  down. 

BOILER  DESIGNING. 

Boiler  designing  is  a  science  and  much  depends  on  the  accuracy 
of  details. 

Modern  engines,  higher  pressure,  and  that  potent  factor  of  the 
times,  competition,  demand  the  greatest  efficiency  from  fuel  and 
engine. 

But  a  few  years  ago  comparatively,  the  rule  was  "thumb"  in  the 
designing  of  a  boiler,  of  "what  had  been  done"  without  any  reason- 
ing ;  this  apparently  when  we  see  some  of  the  boilers  now  in  use ; 
plates,  seams,  rivets,  location  of  same,  brace  design,  number,  and 
method  of  attaching  them,  tubes,  size,  number  and  distribution  ; 
domes,  their  ratio  to  boiler,  old-time  makers  and  engineers  said, 
"one-fifth  the  size  of  boiler  was  a  fair  ratio ;"  all  giving  evidence  that 


MATERIAL.  17 


it  was  no  defined  rule  from  reasoning,  but  following  what  had  been 
done.  Today  the  designing  of  a  boiler  is  a  problem  to  be  worked 
out,  solved  by  factors  entering  into  the  matter ;  location,  space 
economy,  fuel  economy,  engine  design  and  efficiency,  arrangement 
of  furnaces  that  available  heat  can  be  most  completely  absorbed  and 
utilized,  effects  of  contraction  and  expansion,  the  various  types  of 
boiler  must  be  considered  for  their  niche  of  maximum  usefulness, 
for  often  times  one  will  excel  in  certain  duties  and  fail  in  another. 
Requirements  must  be  looked  into  and  the  one  factor,  location, 
would  change  a  design  completely,  for  instance,  where  space  is 
limited,  cost  and  life  may  be  sacrificed,  another  where  fuel  would  bo 
for  life,  again,  locations  where  fuel  must  be  sacrificed,  where  water 
is  bad,  and  a  design  must  be  made  to  suit  the  accessibilities  to  clean. 
Again,  an  illustration  of  what  must  be  considered,  and  the  sacrifice 
for  demands  and  conditions  to  obtain  results,  is  the  fire  engine 
boiler,  life,  cost,  fuel,  and  access  to  clean  and  repair,  all  for  quick 
steaming  qualities.  Then  grate  proportion  for  heating  surface  in 
different  types  of  boiler,  and  the  necessity  of  steam  space  and  tube 
arrangement  to  avoid  obstruction  of  steam  passages  that  retard  cir- 
culation ;  points  which  in  early  boiler  designing  were  badly  neg- 
lected. 

Increased  pressure  has  been  demanded  due  to  space  and  type 
of  engine  would  often  times  vary  proportions. 

The  power  of  boilers  today  is  estimated  from  an  evaporative 
measure,  not  from  the  old-time  commercial  rating,  i.  e.,  so  many 
square  feet  of  heating  surface  per  H.  P.,  leaving  design  or  type  out 
of  the  question.  Thus  we  see  the  importance  of  boiler  designing. 
The  earliest  known  steam  generator  was  a  sphere.  In  the  boiler  of 
Worcester  and  Papin  and  Savery  the  flue  encircled  the  outside  of 
shell.  Newcomen  substituted  that  by  having  a  hemispherical  top 
and  flat  arch  or  bottom.  The  wagon  boiler  designed  by  Watt  re- 
sembled a  wagon  and  hence  its  name.  Boilers  have  been  made  in 
many  and  various  forms,  classified  by  designer's  name,  their  uses  or 
form.  Today  boilers  are  generally  classed  as  internal,  external, 
water  tube,  pipe,  and  sectional  (the  latter  used  extensively  for  heat- 
ing), each  class  usually  bearing  a  name  incident  to  their  use,  such  as 
locomotive  or  marine,  again  boilers  are  further  classed  as  vertical, 
horizontal,  tubular,  cylinder  and  flue. 


CHAPTER  II. 

SELECTION  OF  BOILER. 

In  estimating  the  power  of  a  boiler  it  was  formerly  a  custom  to 
have  a  certain  number  of  square  feet  of  heating  surface  to  repre- 
sent a  H.  P.  (horse  power)  and  the  different  types  were  supposed 
to  have  better  or  inferior  efficiencies  due  to  design  for  instance. 

The  cylinder  type  of  boiler  was  reckoned  from  a  unit  of  10 
square  feet  of  heating  surface  per  horse  power,  the  horizontal 
tubular  type,  12  to  15  square  feet;  the  reason  for  the  difference  was 
the  former  type  of  boiler's  heating  surface  was  considered  as  all 
active  and  exposed  to  the  highest  temperature,  while  the  latter  had 
the  heating  surface  of  tubes  that  was  exposed  to  the  waste  gases 
after  coming  in  contact  with  the  bottom  thus  a  lower  temperature, 
while  as  a  fact  the  tubes  were  thinner  and  had  more  conductivity  for 
heat;  thus  15  square  feet  was  considered  the  unit  of  measurement 
for  that  type. 

Internal  fire  boilers  were  measured  from  the  10  square  feet 
standard. 

But  as  fuels  now  are  valued  by  their  heating  values,  the  amount 
of  water  they  will  evaporate  per  pound  of  class  fuel,  so  with  the 
boiler,  it  must  be  measured  from  its  efficiency  from  an  evaporative 
point,  other  factors  entering  into  its  performances  are  hardness  of 
water  and  temperature  of  feed  water. 

As  the  subject  of  the  steam  boiler  is  one  that  can  be  treated 
almost  inexhaustibly,  it  is  the  writer's  intention  to  devote  this  work 
to  boiler  rules  and  tables  governing  their  construction. 

ENGINE  POWER. 

Power,  or  as  it  is  mechanically  expressed,  heat,  is  measured,  and 
the  unit  of  this  measurement  is  the  amount  of  heat  which  will  raise 
the  temperature  of  one  pound  of  water  one  degree  F  at  its  point  of 
greatest  density  (39  deg.  F.).  The  number  of  heat  units  in  one 
pound  of  water  at  any  given  temperature  is  called  the  "Heat  in 
liquid,"  when  heat  is  applied  to  water  in  open  vessel  the  temperature 

18 


SELECTION  OF  BOILER.  19 

will  rise  until  its  boiling  point  is  reached,  beyond  this  point  no  in- 
crease of  temperature  will  result ;  the  heat  absorbed  being  employed 
in  transforming  the  water  from  liquid  to  steam ;  this  is  called  the 
"heat  of  vaporization,"  and  diminishes  as  the  temperature  and  pres- 
sure increases.  The  "heat  in  liquid,"  added  to  the  "heat  of  vapori- 
zation," is  equal  to  the  total  heat.  The  ratio  of  the  amount  of  heat 
required  to  make  one  pound  of  steam  under  any  given  conditions  to 
that  required  to  make  a  pound  of  steam  from  and  at  212°  is 
called  the  "factor  of  evaporation." 

This  factor  is  found  by  subtracting  the  heat  units  in  one  pound 
of  the  feed  water  at  the  given  temperature  from  the  heat  units  or 
total  heat  of  one  pound  of  the  steam  at  the  given  pressure,  and 
dividing  the  result  by  965.7,  which  is  the  heat  of  vaporization,  or 
number  of  heat  units  required  to  evaporate  one  pound  of  water  at 
212°  into  steam  at  212°. 

The  total  number  of  pounds  of  water  to  be  evaporated  per  hour 
under  a  given  steam  pressure  multiplied  by  its  particular  factor  of 
evaporating  gives  us  the  "equivalent  evaporation,"  from  and  at 
212°,  or  in  other  words,  the  amount  of  water  which  would  have 
been  evaporated,  with  the  same  amount  of  fuel,  had  the  feed  water 
been  at  212  degrees  and  the  pressure  that  of  the  atmosphere. 

Assuming  an  engine  to  be  one  of  200  H.  P.  and  the  boiler  to  be 
selected  according  to  the  commercial  rating  of  boilers.  The  given 
data  to  determine  from  would  be : 

200  HP  engine, 
engine  taking  20  Ibs.  of  steam  per  HP  per  hour 

120  absolute  pressure    (by  gauge   105) 

190°  temperature  of  feed  water 
the  evaporation  of  34.5  Ibs.  of  water  at  212°. 

As  stated,  the  number  of  pounds  of  water  to  be  evaporated  to 
produce  a  horse  power  from  an  engine  will  be  computed  from  the 
type  of  engine  used.  See  table  of  engine  efficiencies,  Standards  of 
Steam  Engine. 


20 


THE  BOILER. 
TABLE  OF  STANDARD  OF  STEAM  ENGINES. 


TYPE   OF  BOILERS. 

TYPE   OF  ENGINES. 

1  0  t*<2 

PH  Q    03    « 

as  y  *-j  o 

i>     C     J^     O     r/i 

&§  8/8 

bjo  '   <u 
IS  * 

M            c/3 

iif* 

S  C0 

d«£ 

8  ^o 

'w  ^  w 

|P 

1i;i 

D          O 

OfM  S3 

VH 

C   -M    ^ 

^  'SjOO 

I88 

**% 

%  w£ 

0)        '~l 

c  S  T4" 

P3 

g  rt^-  3 

MM    «^     fe^ 

°;§^ 
•§1.1*1 
Stlli 

o  offi^^ 

^^^^0 

llfj! 

imple  non-  co 
automatic  cu 
gine,  steam 
80  to  90  Ibs. 

imple  condens 
matic  cut-off 
steam  pressu 
90  Ibs. 

«£s 

-  1 

C  W)AW- 

3     G     rj  ,Q 

5'fi  §-* 

g£|S 

5T3    W-l 

80j  t—  1 
<D 
-M   O 

W  +j 

•^  g  $w 

^ 

PM 

c/2 

O 

O 

H 

Water  consumption  of  dif- 

ferent   types    of    engines 

per  1  HP  per  hour  

32  Ibs 

22  Ibs. 

20  Ibs. 

16  Ibs 

13  Ibs. 

Coal  consumption  per  1  HP 

per  hour  with  a  modern 

water  tube  boiler  

3^  Ibs. 

2Y2  Ibs. 

2^  Ibs. 

1M  Ibs. 

l^lbs. 

Coal  consumption  per  1  HP 

per  hour  with  a  common 
HT  boiler  

4  Ibs. 

3  Ibs. 

2%  Ibs. 

2M  Ibs. 

1%  Ibs. 

RULES  FOR  CALCULATION. 

THE    CIRCLE. 

Multiply  diameter  by  3.1416  to  find  circumference.  Multiply  cir- 
cumference by  .31831  to  find  diameter.  Multiply  square  of  diameter 
by  .7854  to  find  area.  Multiply  the  square  root  of  area  by  1.12837 
to  find  diameter.  Multiply  diameter  by  .8862  to  find  side  of  a  square 
equal  to  area.  Multiply  diameter  by  .7071 — product  is  side  of  an 
inscribed  square. 

Rule  to  find  area  of  a  circular  ring  formed  by  two  concentric 
circles:  Multiply  the  sum  of  the  two  diameters  by  their  difference 
and  the  product  by  .7854 — the  result  is  area.  Multiply  radius  by 
6.2831  to  find  circumference. 

Rule  to  find  area  of  a  section  of  a  circle :  Multiply  one-half  the 
length  of  arc  by  the  radius  of  circle. 

Rule  to  find  area  of  a  sector :  Multiply  length  of  arc  by  the 
radius  and. divide  the  product  by  2  for  the  area. 


SELECTION  OF  BOILER.  21 

EXAMPLE: 

50"  =  length  of  arc  of  sector 
30" -radius 


2)1500 


750  =area  of  sector 

Rule  to  find  area  of  a  triangle :     Multiply  base  by  height  and 
divide  the  product  by  2  for  the  area. 

EXAMPLE: 

38"  =base  of  triangle 
20"  =  height  of  triangle 

2)760 


380  =area  of  triangle 

Rule  to  find  area  of  a  segment  of  a  circle :  Subtract  area  of 
triangle  from  area  of  sector.  The  result  will  be  the  area  of  seg- 
ment. 

EXAMPLE: 

750  =area  of  sector 
380  =area  of  triangle 

370  ==area  of  segment 

Rule  to  find  one  dimension  of  triangle  when  area  and  one 
dimension  is  given  :  Double  the  area  and  divide  by  given  dimension. 

Rule  to  find  area  of  triangle  when  dimensions  of  three  sides  are 
given :  From  half  the  sum  of  the  three  sides,  subtract  each  side 
separately ;  multiply  the  half  sum  and  the  three  remainders  to- 
gether ;  the  square  root  of  the  product  is  the  area. 

Rule  to  find  hypothenuse  of  a  triangle  when  dimensions  of  base 
and  perpendicular  are  given :  Extract  the  square  root  of  the  sum 
of  the  squares  of  the  base  and  the  perpendicular ;  the  result  is  the 
length  of  hypothenuse. 

Rule  to  find  the  base  or  perpendicular  when  hypothenuse  is 
given :  Extract  the  square  root  of  the  difference  between  the  square 
of  the  squares  of  the  base  and  the  perpendicular ;  the  result  is  the 
required  side. 

QUADRILATERALS. 

Rule  to  find  area  of  a  parallelogram :  Multiply  base  by  altitude. 
Rule  to  find  area  of  a  trapezoid :  Multiply  one-half  sum  of  the 
parallel  sides  by  the  altitude. 


22  THE  BOILER. 

Rule  to  find  area  of  a  trapezium :  Multiply  the  diagonal  by  one- 
half  sum  of  the  perpendiculars  drawn  to  it  from  the  vertices  of 
opposite  angle. 

Rule  to  find  area  of  a  rectangle :     Multiply  length  by  width. 

Doubling  the  diameter  of  a  circle  increases  its  area  four  times. 

The  side  of  a  square  multiplied  by  1.128  equals  diameter  of 
circle  of  equal  area. 

Rule  to  find  volume  of  a  pyramid  or  cone :  Multiply  the  area  of 
the  base  by  one-third  the  altitude. 

Rule  to  find  the  convex  surface  of  a  frustrum  of  a  pyramid  or  of 
a  cone :  Multiply  the  sum  of  the  perimeters  or  of  the  circumference 
by  one-half  the  slant  height. 

Rule  to  find  the  volume  of  a  frustrum  of  a  pyramid  or  of  a  cone : 
To  the  sum  of  the  areas  of  both  bases  add  the  square  root  of  the 
product  and  multiply  this  sum  by  one-third  of  the  altitude. 

THE  SPHERE. 

Rule  to  find  the  surface  of  a  sphere :  Multiply  the  diameter  by 
the  circumference  of  a  great  circle  of  a  sphere. 

Rule  to  find  the  volume  of  a  sphere :  Multiply  the  surface  by  1/6 
of  the  diameter  or  1/3  of  the  radius. 

Rule  to  find  the  three  dimensions  of  a  rectangular  solid,  the 
volume  and  ratio  of  the  dimensions  being  given :  First,  divide  the 
volume  by  the  product  of  the  terms  proportional  to  the  three  dimen- 
sions, and  extract  the  cube  root  of  the  quotient.  Second,  multiply 
the  root  obtained  by  each  proportional  term ;  the  products  will  be  the 
corresponding  side. 

Rule  to  find  solidity  of  a  sphere :  Multiply  cube  of  diameter  by 
.5236. 

Rule  to  find  surface  of  a  ball :  Multiply  square  of  diameter  by 
3.1416. 


UNIVERSITY 

OF      . 


SELECTION  OF  BOILER.  23 

A    TRAPEZOID. 


A  plane  four  sided  figure  having  two  of  the  opposite  sides 
parallel  to  each  other. 

Rule  to  find  area  of  a  trapezoid  whose  sides  are  26"  and  14" 
altitude  10" :  Multiply  one-half  the  sums  of  parallel  sides  by  the 
altitude. 

EXAMPLE: 
26" 
14 

2)40 

20 
10 

200     area  of  trapezoid 

SOLIDS. 

Rule  to  find  volume  of  a  prism  or  cylinder :  Multiply  area  of  the 
base  by  the  altitude. 

Rule  to  find  convex  surface  of  a  prism  or  cylinder :  Multiply  the 
perimeter  or  circumference  of  the  base  by  the  altitude. 

SIGNS  USED   IN  MATHEMATICAL  CALCULATIONS. 
77  Ratio  of  circumference  of  a  circle  to  a  diam.,  as  3.1416 

Equal,  as  12  inches  =1  foot 
+  Plus ,  addition ,  as  2  +  4  =  6 

Minus,  substraction,  as  8-4=4 

Multiply,  as  4x4  =  16 
-r-  Divide,  as  10 -=-2  =5 

:      :   :    Proportion,  as  2    :  4    ::  8  :  16;  or  2  is  to  4  as  8  is  to  16 
x/  Square  root  is  required;  cube  root,  3\/27  =3 

52  Number  is  to  be  squared,  52  =25 

53  Number  is  to  be  cubed,  53  =  125 
Decimal  point,  as  .1  =  110;    .14=^% 

()  Parenthesis,  all  numbers  between  to  be  taken  as  one 

Vinculum  signifies  the  numbers  over  which  it  is  placed  are  to  be 

taken  together. 
Degrees 

Minutes  or  feet 
Seconds  or  inches 

A  coefficient  is  a  prescribed  amount  to  make  up  for  any  defects 
reducing  the  strength  of  plate  due  to  punching,  caulking,  etc. 

A  factor  of  safety  is  the  difference  between  the  safe  working 
and  bursting  pressures. 


24 


THE  BOILER. 
CIRCUMFERENCES  AND  AREAS  OF  CIRCLES. 


OF  ONE  INCH. 

OF  INCHES  OR  FEET. 

Fract. 

Dec. 

Circ. 

Area 

Dia. 

Circ. 

Area 

Dia. 

Circ. 

Area. 

1-64 

.015625 

.04909 

.00019 

1 

3.1416 

.7854 

64 

201.06 

3216.99 

1-32 

.03125 

.09818 

.00077 

2 

6  .  2832 

3.1416 

65 

204  .  20 

3318.31 

3-64 

.046875 

.  14726 

.00173 

3 

9  .  4248 

7.0686 

66 

207  .  34 

3421.19 

.0625 

.  19635 

.00307 

4 

12  .  5664 

12.5664 

67 

210.49 

3525  .  65 

5-64 

.078125 

.  24545 

.  00479 

5 

15.7080 

19.635 

68 

213.63 

3631.68 

3-32 

.09375 

.  29452 

.00690 

6 

18.850 

28  .  274 

69 

216.77 

3739.28 

7-64 

.  109375 

.34363 

.  00939 

7 

21.991 

38.485 

70 

219.91 

3848  .  45 

1-8 

.125 

.39270 

.01227 

8 

25.133 

50  .  266 

71 

223.05 

3959  .  19 

9=64 

.  140625 

.44181 

.01553 

9 

28  .  274 

63.617 

72 

226.19 

4171.50 

5=32 

.  15625 

.49087 

.01917 

10 

31.416 

78.540 

73 

229.34 

4185.39 

11=64 

.171875 

.53999 

.02320 

11 

34  .  558 

95.033 

74 

232.48 

4300.84 

3=16 

.1875 

.  58905 

.02761 

12 

37.699 

113.1 

75 

235  .  62 

4417.86 

13=64 

.203125 

.63817 

.03241 

13 

40.841 

132.73 

76 

238  .  76 

4536.46 

7=32- 

.21875 

.68722 

.03758 

14 

43  .  982 

153.94 

77 

241.90 

4656.63 

15-64 

.234375 

.  73635 

.04314 

15 

47.124 

176.71 

78 

245.04 

4778.36 

1=4 

.25 

.  78540 

.04909 

16 

50  .  265 

201.06 

79 

248  .  19 

4901.67 

17=64 

.  265625 

.83453 

.05542 

17 

53.407 

226.98 

80 

251.33 

5026.55 

9=32 

.28125 

.88357 

.06213 

18 

56.549 

254.47 

81 

254.47 

5153. 

19=64 

.  296875 

.93271 

.06922 

19 

59  .  690 

283  .  53 

82 

257.61 

5281.02 

5-16 

.3125 

.98175 

.07670 

20 

62  .  832 

314.16 

83 

260  .  75 

5410.61 

21=64 

.328125 

.0309 

.  08456 

21 

65  .  973 

346.36 

84 

263.89 

5541.77 

11=32 

.34375 

.0799 

.09281 

22 

69.115 

380  .  13 

85 

267.04 

5674  .  50 

23=64 

.359375 

.1291 

.  10144 

23 

72.257 

415.48 

86 

270  .  18 

5808.80 

3=8 

.375 

.1781 

.11045 

24 

75  .  398 

452.39 

87 

273  .  32 

5944  .  68 

25=64 

.390625 

.2273 

.11984 

25 

78  .  540 

490  .  87 

88 

276.46 

6082.12 

13=32 

.40625 

.2763 

.  12962 

26 

81.681 

530.93 

89 

279.60 

6221.14 

27=64 

.421875 

1.3254 

.  13979 

27 

84  .  823 

572  .  56 

90 

282  .  74 

6361.73 

7=16 

.4375 

1.3744 

.  15033 

28 

87.965 

615.75 

91 

285.88 

6503.88 

29=64 

.453125 

1.4236 

.16126 

29 

91  .  106 

660  .  52 

92 

289  .  03 

6647.61 

15=32 

.46875 

1.4726 

.  17257 

30 

94  .  248 

706.86 

93 

292.17 

6792.91 

31=64 

.484375 

1.5218 

.  18427 

31 

97.389 

754  .  77 

94 

295.31 

6939.78 

1=2 

.5 

1.5708 

.  19635 

32 

100.53 

804.25 

95 

298.45 

7088  .  22 

33=64 

.515625 

1.6199 

.  20880 

33 

103.67 

855  .  30 

96 

301.59 

7238  .  23 

W 

.53125 
.  546875 

1  .  6690 
1.7181 

.22166 
.  23489 

34 
35 

106.81 
109  .  96 

907.92 
962.11 

97 

98 

304  .  73 
307.88 

7339.81 
7542  .  96 

9-16 

.5625 

1.7671 

.24850 

36 

113.10 

1017.88 

99 

311.02 

7697.69 

37=64 

.578125 

1.8163 

.  26248 

37 

116.24 

1075.21 

100 

314.16 

7853  .  98 

19=32 

.59375 

1.8653 

.  27688 

38 

119.38 

1134.11 

101 

317.30 

8011.85 

39=64 

.609375 

1.9145 

.29164 

39 

122.52 

1194.59 

102 

320.44 

8171.28 

5=8 

.625 

1.9635 

.  30680 

40 

125.66 

1256.64 

103 

323  .  58 

8332.29 

41=64 

.  640625 

2.0127 

32232 

41 

128.81 

1320.25 

104 

326.73 

8494.87 

21=32 

.65625 

2.0617 

.33824 

42 

131.95 

1385.44 

105 

329.87 

8659.01 

43=64 

.671875 

2.1108 

.35453 

43 

135.09 

1452  .  20 

106 

333.01 

8824  .  73 

11=16 

45=64 

.6875 
.703125 

2.1598 
2  .  2090 

.37122 

.38828 

44 
45 

138.23 
141.37 

1520.53 
1590.43 

107 
108 

336.15J  8992.02 
339.29|  9160.88 

23=32 

.71875 

2  .  2580 

.  40574 

46 

144.51 

1661.90 

109 

342.43 

9331.32 

47=64 

.  734375 

2.3072 

.42356 

47 

147.65 

1734.94 

110 

345.58 

9503.32 

3=4 

.75 

2.3562 

.44179 

48 

150.80 

1809  .  56 

111 

348  .  72 

9676.89 

49=64 

.  765625 

2.4054 

.45253 

49 

153.94 

1885  .  74 

112 

351.86 

9852.03 

W 

13=16 

.78125 
.  796875 
.8125 

2.4544 
2.5036 
2  .  5525 

.47937 
.49872 
.51849 

50 
51 
52 

157.08 
160.22 
163.36 

1963.50 
2042.82 
2123.72 

113 
114 
115 

355. 
358.14 
361.28 

10028  .  75 
10207.03 
10386.89 

53=64 

.828125 

2.6017 

.53862 

53 

166.50 

2206  .  18 

116 

364.42 

10568.32 

27=32 

.84375 

2.6507 

.55914 

54 

169.65 

2290.22 

117 

367  .  57 

10751.32 

55=64 

.859375 

2  .  6999 

.  58003 

55 

172.79 

2375.83 

118 

370.71 

10935  .  88 

7=8 

.875 

2  .  7489 

.60132 

56 

175.93 

2463.01 

119 

373.85 

11122.02 

57-64 

.  890625 

2.7981 

.62298 

57 

179.07  1  2551.76 

120 

376.99 

11309.73 

29=32 

.90625 

2.8471 

.  64504 

58 

182.21   1  2642.08 

121 

380  .  13 

11499.01 

59=64 

.921875 

2  .  8963 

.  66746 

59 

185.35 

2733.97 

122 

383  .  27 

11689.87 

15=16 

.9375 

2.9452 

.  69029 

60 

188.50 

2827.43 

123 

386.42 

11882.29 

61=64 

.953125 

2  .  9945 

.71349 

61 

191.64 

2922.47 

124 

389  .  56 

12076.28 

31=32 

.96875 

3.0434 

.  73708 

62 

194.78 

3019.07 

125 

392  .  70 

12271.85 

63-64 

.984375 

3  .  0928 

.  76097 

63 

197.92 

3117.25 

126   395.84 

12468.98 

SELECTION  OF  BOILER. 


25 


AREAS  OF  CIRCLES  FROM  ^  INCH  UP  TO  10  INCHES  IN  DIAMETER,  ADVANCING 
BY  THIRTY-SECONDS  OF  AN  INCH. 

INCHES. 


0" 

1" 

2" 

3" 

4" 

5" 

6" 

7" 

8" 

9" 

0 

.7854 

3.1416 

7.068 

12.56 

19.63 

28.27 

38.48 

50.26 

63.62 

0 

3*2 

'  000767 

.8352 

3.240 

7.216 

12.76 

19.88 

28.57 

38.83 

50.66 

64.06 

3*2" 

A 

.00306 

.8866 

3.341 

7.366 

12.96 

20.13 

28.87 

39.17 

51.05 

64.50 

A 

A 

.0069 

.9395 

3.443 

7.516 

13.16 

20.38 

29.16 

39.52 

51.45 

64.95 

A 

H 

.0123 

.9940 

3.546 

7.669 

13.36 

20.63 

29.46 

39.87 

51.85 

65.40 

Ys 

_5_ 

.0192 

1.050 

3.651 

7.824 

13.57 

20.88 

29.77 

40.22 

52.25 

65.84 

& 

_^ 

.0276 

1.107 

3.758 

7.970 

13.77 

21.13 

30.07 

40.57 

52.65 

66.30 

A 

J^ 

.0376 

1.166 

3.866 

8.137 

13.98 

21.39 

30.37 

40.93 

53.05 

66.75 

.0491 

1.227 

3.976 

8.295 

14.19 

21.65 

30.68 

41.28 

53.46 

67.20 

F 

.0621 

1.289 

4.087 

8.456 

14.40 

21.91 

30.99 

41.64 

53.86 

67.65 

& 

A 

.0767 

1.353 

4.199 

8.618 

14.61 

22.17 

31.30 

42.00 

54.27 

68.11 

A 

1^ 

.0928 

1.418 

4.314 

8.781 

14.82 

22.43 

31.61 

42.36 

54.68 

68.57 

44 

H 

.1104 

1.484 

4.430 

8.946 

15.03 

22.69 

31.92 

42.72 

55.09 

69.03 

4* 

.1296 

1.553 

4.547 

9.112 

15.25 

22.95 

32.23 

43.08 

55.50 

69.49 

M 

T^ 

.1503 

1.623 

4.666 

9.280 

15.47 

23.22 

32.55 

43.45 

55.91 

69.95 

•& 

M 

.1725 

1.694 

4.786 

9.450 

15.68 

23.49 

32.86 

43.81 

56.33 

70.42 

M 

H 

.1963 

1.767 

4.908 

9.621 

15.90 

23.76 

33.18 

44.18 

56.74 

70.88 

4i 

.2216 

1.840 

5.032 

9.794 

16.13 

24.03 

33.50 

44.55 

57.16 

71.35 

44 

.2485 

1.917 

5.157 

9.968 

16.35 

24.30 

33.82 

44.92 

57.58 

71.82 

T% 

M 

.2770 

1.994 

5.283 

10.14 

16.57 

24.58 

34.15 

45.29 

58.00 

72.29 

® 

^ 

.3067 

2.073 

5.411 

10.32 

16.80 

24.85 

34.47 

45.66 

58.43 

72.76 

6/s 

21 

.3382 

2.154 

5.541 

10.50 

17.03 

25.13 

34.80 

46.04 

58.85 

73.23 

§4 

II 

.3712 

2.236 

5.672 

10.68 

17.26 

25.41 

35.12 

46.41 

59.28 

73.71 

tt 

M 

.4057 

2.319 

5.805 

10.86 

17.49 

25.68 

35.45 

46.79 

59.70 

74.18 

Jf 

.4417 

2.405 

5.939 

11.04 

17.72 

25.97 

35.78 

47.17 

60.13 

74.66 

M 

.4793 

2.492 

6.075 

11.23 

17.95 

26.25 

36.11 

47.55 

60.56 

75.14 

M 

*t 

.5184 

2.581 

6.212 

11.41 

18.19 

26.53 

36.45 

47.94 

60.99 

75.62 

i| 

.5591 

2.669 

6.351 

11.60 

18.43 

26.82 

36.79 

48.32 

61.24 

76.10 

M 

j^ 

.6013 

2.761 

6.491 

11.79 

18.66 

27.11 

37.12 

48.71 

61.86 

76.59 

Ji 

j 

§1 

.6450 

2.854 

6.633 

11.98 

18.91 

27.40 

37.46 

49.09 

62.30 

77.07 

ft 

it 

.6903 

2.948 

6.777 

12.18 

19.15 

27.69 

37.80 

49.48 

62.74 

77.56 

H 

.7370 

3.044 

6.922 

12.37 

19.39 

27.98 

38.14 

49.87 

63.18 

78.05 

M 

26 


THE  BOILER. 
DECIMALS  OF  A  FOOT  FOR  EACH 


OF  AN  INCH. 


INCH 

0" 

1" 

2" 

3" 

4" 

5" 

6" 

'  7" 

8" 

9" 

10" 

11" 

0 

0 
.0026 

.0833 
.0859 

.1667 
.1693 

.2500 
.2526 

.3333 
.3359 

.4167 
.4193 

.5000 
.5026 

.5833 
.  5859 

.6667 
.  6693 

.7500 
.7526 

.8333 
.8359 

.9167 
.9193 

iV 

.0052 

.0885 

.1719 

.  2552 

.3385 

.4219 

.5052 

.  5885 

.6719 

.7552 

.8385 

.9219 

.0078 

.0911 

.  1745 

.2578 

.3411 

.4245 

.5078 

.5911 

.6745 

.7578 

.8411 

.9245 

H 

.0104 

.0937 

.1771 

.2604 

.3437 

.4271 

.5104 

.5937 

.6771 

.  7604 

.8437 

.9271 

« 

.0130 

.0964 

.1797 

.  2630 

.3464 

.4297 

.5130 

.5964 

.6797 

.7630 

.8464 

.9297 

ft 

.0156 

.0990 

.1823 

.2656 

.3490 

.4323 

.5156 

.5990 

.6823 

.7656 

.8490 

.9323 

T7 

.0182 

.1016 

.1849 

.2682 

.3516 

.4349 

.5182 

.6016 

.6849 

.7682 

.8516 

.  9349 

H 

.0208 

.1042 

.1875 

.2708 

.3542 

.4375 

.5208 

.  6042 

.6875 

.7708 

.8542 

.9375 

& 

.0234 

.1068 

.1901 

.2734 

.3568 

.4401 

.5234 

.6068 

.6901 

.7734 

.8568 

.9401 

-h 

.0260 

.1094 

.1927 

.2760 

.3594 

.4427 

.  5260 

.6094 

.6927 

.7760 

.8594 

.9427 

1 

.0286 

.1120 

.1953 

.2786 

.3620 

.4453 

.5286 

.6120 

.6953 

.7786 

.8620 

.  9453 

.0312 

.1146 

.1979 

.2812 

.3646 

.4479 

.5312 

.6146 

.6979 

.7812 

.8646 

.9479 

if 

.  0339 

.1172 

.  2005 

.2839 

.3672 

.  4505 

.5339 

.6172 

.7005 

.7839 

.8672 

.9505 

j_ 

.0365 

.1198 

.2031 

.  2865 

.3698 

.4531 

.  5365 

.6198 

.7031 

.  7865 

.8698 

.9531 

M 

.0391 

.1224 

.2057 

.2891 

.3724 

.4557 

.5391 

.6224 

.7057 

.7891 

.8724 

.9557 

V* 

.0417 

.1250 

.  2083 

.2917 

.3750 

.4583 

.5417 

.  6250 

.7083 

.7917 

.8750 

.9583 

H 

.0443 

.1276 

.2109 

.  2943 

.3776 

.4609 

.5443 

.6276 

.7109 

.7943 

.8776 

.9609 

j»_ 

.0469 

.1302 

.2135 

.2969 

.3802 

.4635 

.5469 

.  6302 

.7135 

.7969 

.8802 

.9635 

41 

.0495 

.1328 

.2161 

.2995 

.3828 

.4661 

.5495 

.6328 

.7161 

.7995 

.8828 

.9661 

H 

.0521 

.1354 

.2188 

.3021 

.3854 

.4688 

.5521 

.6354 

.7188 

.8021 

.8854 

.9688 

.0547 

.  1380 

.2214 

.3047 

.  3880 

.4714 

.5547 

.  6380 

.7214 

.8047 

.8880 

.9714 

.0573 

.1406 

.2240 

.3073 

.  3906 

.4740 

.5573 

.6406 

.  7240 

.8073 

.8906 

.9740 

.0599 

.  1432 

.2266 

.3099 

.3932 

.4766 

.5599 

.6432 

.7266 

.8099 

.8932 

.9766 

M 

.0625 

.1458 

9i?go 

.3125 

.3958 

.4792 

.5625 

.6458 

.7292 

.8125 

.8958 

.9792 

ii 

.0651 

.1484 

.2318 

.3151 

.  3984 

.4818 

.5651 

.6484 

.7318 

.8151 

.8984 

.9818 

.13 

.0677 

.1510 

.2344 

.3177 

.4010 

.4844 

.5677 

.6510 

.7344 

.8177 

.9010 

.9844 

p. 

.  0703 

.  1536 

.2370 

.3203 

.  4036 

.4870 

.5703 

.6536 

.7370 

.8203 

.9036 

.9870 

78 

.0729 

.1562 

.  2396 

.3229 

.  4062 

.4896 

.5729 

.  6562 

.7396 

.8229 

.9062 

.9896 

.0755 

.1589 

2422 

.3255 

.  4089 

.4922 

.5755 

.6589 

.  7422 

.8255 

.  9089 

.9922 

.0781 

.1615 

|  '.2448 

.3281 

.4115 

.4948 

.5781 

.6615 

.7448 

.8281 

.9115 

.9948 

.0807 

.1641 

.2474 

.3307 

.4141 

.4974 

.5807 

.6641 

.7474 

.8307 

.9141 

.9974 

1 

1  .  0000 

HORSE  POWER  MEASUREMENT. 

In  calculating  the  H.  P.  boiler  required  for  a  given  engine  it  is 
customary  to  calculate  what  amount  of  water  would  be  evaporated 
per  hour  at  the  temperature  of  212  atmospheric  pressure. 

The  ratio  of  the  amount  of  heat  required  to  make  one  pound  of 
steam  under  any  given  condition  to  that  required  to  make  a  pound 
of  steam  from  212°  is  called  the  factor  of  evaporation,  and  this  is 
found  by  subtracting  the  heat  units  in  one  pound  of  the  feed  water 
at  the  given  temperature,  from  the  heat  units  in  one  pound  of  steam 
at  the  given  pressure,  and  dividing  the  result  by  965.7,  which  is  the 
heat  of  evaporation,  or  number  of  heat  units  required  to  evaporate 
one  pound  of  water  at  212°  into  steam  of  212°. 


SELECTION  OF  BOILER.  27 

The  number  of  pounds  of  water  to  be  evaporated  per  hour  under 
a  given  steam  pressure,  multiplied  by  its  particular  factor  of  evap- 
oration, gives  the  factor  of  evaporation  from  and  at  212°  (or  the 
amount  of  water  which  would  have  been  evaporated  with  the  same 
amount  of  fuel,  had  the  feed  water  been  at  212  degrees  atmospheric 
pressure. 

Hence  it  is  first  necessary  to  find  the  amount  of  water  the  engine 
is  to  use  per  hour ;  then  the  factor  of  evaporation  and  the  product  of 
these  two  will  be  the  equivalent  from  and  at  212°  ;  34T/2  pounds  of 
water  at  212°  evaporated  into  steam  at  atmospheric  pressure 
equals  a  horse  power ;  dividing  the  equivalent  evaporation  by  34*/2 
gives  the  horse  power  required. 

Rule  to  find  capacity  of  boiler  for  any  engine,  this  according  to 
the  commercial  rating  of  boilers :  Multiply  the  horse  power  of 
the  engine  by  the  number  of  pounds  of  steam  the  engine  will- con- 
sume per  indicated  horse  power  per  hour  and  call  this  product 
No.  1  ;  from  the  number  of  heat  units  contained  in  one  pound 
of  the  steam  at  absolute  pressure  subtract  the  number  of  heat  units 
in  one  pound  of  feed  water,  and  divide  by  965.7  to  get  factor  of  evap- 
oration, and  call  this  product  No.  2;  multiply  product  No.  1 
by  product  No.  2  and  divide  by  34^  (the  number  of  pounds  of 
water  evaporated  from  and  at  212°,  to  develop  one  horse  power), 
and  this  product  will  be  the  required  commercial  rating  of  boiler. 


LEGEND: 

E  =  Power  of  engine 

=  Lbs.  of  steam  per  horse  power 
P  =  Pressure 

T  =  Temperature  of  feed  water 

W  =  Water  to  be  evaporated  per  HP  per  hour 

TSH       =  Total  heat  units  in  steam 
HU         =Heat  units  in  feed  water 
HE         =Heat  of  evaporation 
FE          =  Factor  of  evaporation 
W  of  W  =  Weight  of  water  used  per  HP  per  hour 


FORMULA: 

E  x  L  X    (TSH— HU- 965.  7) 

-   =  commercial  rating  of  boiler. 


28  THE  BOILER. 

No.  1     200     HP  engine 

20  No.  of  Ibs.  of  steam  per  HP  per  hour 

4000  =the  weight  in  Ibs.  of  water  used  per  hour 
No.  2 

Heat  units  to 

evaporate  one  1217 .  9445  =  total  heat  of  given  steam 

Ib.  of  water  at  190 .  643     =heat  units  in  feed  water 

212°  into  steam 

at  212°=  965.7)1027.3015(1.063  factor  of  evaporation 

965   7 


61  601 
57  942 

3  6595 

2  8971 

7624 

1 .  063         factor  of  evaporation  =  product  No.  2 

4000  weight  of  water  in  Ib.  use  per  hour  =  product  No.  1 

4252.000  the  equivalent  evaporation  from  and  at  212°  F. 

Weight  of  water 
required  per  hour 
per  HP  for  high 

pressure  engine  =    34 .  5 )  4252 .  000  (123 .  24  commercial  HP  of  boiler  required 
345 

802 
690 


1120 

1035  This  example  was  figured  on  a 

basis  of  34i^  Ibs.  of  water  per 
850  engine  HP.    The  consumption 

690  of  steam   of   modern   engine, 

per  HP,  varies  in  limits,  de- 
1600  pending  on  type  of  engine. 

1380 


220 


PROPERTIES  OF  STEAM. 

The  temperature  at  which  water  is  converted  into  steam  varies 
with  the  pressure.  At  atmospheric  the  steaming  point  is  212  de- 
grees F.,  less  at  low  pressure  and  higher  at  higher  pressure.  When 
water  reaches  the  boiling  point,  further  addition  of  heat  effects  no 
change  in  temperature,  the  heat  absorbed  in  producing  steam 
having  the  same  temperature  and  pressure  as  that  at  which  it  is 


SELECTION  OF  BOILER. 


29 


evaporated.  The  heat  thus  absorbed  is  known  as  the  latent  heat,  so 
called  because  it  produces  effects  other  than  those  of  change  of  tem- 
perature. The  amount  of  heat  rendered  latent  by  each  pound  of 
water  in  becoming  steam  varies  with  the  pressure,  decreasing  as  the 
pressure  rises.  The  latent  heat  added  to  the  sensible  heat  (this 
latter  as  shown  by  the  thermometer)  gives  the  total  heat,  this  term 
used  to  designate  the  number  of  heat  units  contained  in  one  pound 
of  steam  above  a  given  temperature.  Total  heat  is  calculated  from 
32  degrees  F.  as  the  total  heat  is  greater  the  higher  the  pressure ; 
the  amount  of  fuel  necessary  to  evaporate  a  pound  of  water  in- 
creases with  the  pressure ;  saturated  steam  cannot  be  superheated  in 
contact  with  water,  that  is,  its  temperature  cannot  be  raised  above 
the  point  normal  to  the  pressure,  neither  can  it  be  cooled  without 
change  of  pressure,  for  any  loss  of  heat  is  compensated  by  the  latent 
heat  of  the  steam  which  is  condensed. 

Saturated  steam  is  that  which  has  the  minimum  temperature  at 
which  it  can  exist  as  a  vapor  under  the  given  pressure. 

Superheated  steam  has  a  temperature  higher  than  that  of  satura- 
tion at  the  same  pressure.  The  same  pressure  above  vacuum  is  the 
gauge  pressure  plus  14.7  pounds. 

TABLE 
PRESSURE  OF  STEAM  AT  DIFFERENT  TEMPERATURES. 


Pounds 

pressure 
per  square 
inch  above 
vacuum 

Temperature 
Fahr. 

Heat  units  in 
water  above 
32" 

Latent  heat  in 
Heat  of 
Vaporization 

Total 
heat  units 
above  32" 

Volume  of 
one  pound  in 
cubic  foot 

1 

101.99 

70.0 

1043  .  0 

1113.1 

334.5 

5 

162.34 

130.7 

1000.8 

1131.5 

73.21 

10 

193.25 

161.9 

979.0 

1140.9 

38.15 

15 

213.03 

181.8 

965.1 

1146.9 

26.14 

20 

227.95 

196.9 

954.6 

1151.5 

19.91 

25 

240.04 

209.1 

946.0 

1155.1 

16.13 

30 

250.72 

219.4 

938.9 

1158.3 

13.59 

35 

259.19 

228.4 

932.6 

1161.0 

11.75 

40 

267.13 

236.4 

927.0 

1163.4 

10.37 

45 

274.29 

243.6 

922.0 

1165.6 

9.285 

50 

280.85 

250.2 

917.4 

'    1167.6 

8.418 

55 

286.89 

256.3 

913.1 

1169.4 

7.698 

60 

292.51 

261.9 

909.3 

1171.2 

7.097 

65 

297.77 

267.2 

905.5 

1172.7 

6.583 

70 

302.71 

272.2 

902.1 

1174.3 

6.143 

75 

307.38 

276.9 

898.8 

1175.7 

5.760 

30 


THE  BOILER. 
PRESSURE  OF  STEAM  AT  DIFFERENT  TEMPERATURES. 


Pounds 
pressure 
per  square 
inch  above 
vacuum 

Temperature 
Fahr. 

Heat  units  in 
water  above 

32" 

Latent  heat  in 
Heat  of 
Vaporization 

Total 
heat  units 
above  32" 

Volume  of 
of  one  pound 
cubic  foot 

80 

311.80 

281.4 

895.6 

1177.0 

5.426 

85 

316.02 

285.8 

892.5 

1178.3 

5.126 

90 

320.04 

290.0 

889.6 

1179.6 

4.859 

95 

323.89 

294.0 

886.7 

1180.7 

4.619 

100 

327.58 

297.9 

884.0 

1181.9 

4.403 

105 

331.13 

301.6 

881.3 

1182.9 

4.205 

110 

334.56 

305.2 

878.8 

1184.0 

4.026 

115 

337.86 

308.7 

876.3 

1185.0 

3.862 

120 

341.05 

312.0 

874.0 

1186.0 

3.711 

125 

344.13 

315.2 

871.7 

1186.9 

3.572 

130 

347.12 

318.4 

869.4 

1187.8 

3.444 

135 

350.03 

321.4 

867.3 

1188.7 

3.323 

140 

352.85 

324.4 

865.1 

1189.5 

3.212 

145 

355.59 

327.2 

863.2 

1190.4 

3.107 

150 

358.26 

330.0 

861.0 

1191.2 

3.011 

155 

360.86 

332.7 

859.3 

1192.0 

2.919 

160 

363.40 

335.4 

857.4 

1192.8 

2.833 

165 

365.88 

338.0 

855.6 

1193.6 

2.751 

170 

368.29 

340.5 

853.8 

1194.3 

2.676 

175 

370.65 

343.0 

852.0 

1195.0 

2.603 

180 

372.97 

345.4 

850.3 

1195.7 

2.535 

185 

375.23 

347.8 

848.6 

1196.4 

2.470 

190 

377.44 

350.1 

847.0 

1197.1 

2.408 

195 

379.61 

352.4 

845.3 

1197.7 

2.349 

200 

381.73 

354.6 

843.8 

1198.4 

2.294 

205 

383.82 

356.8 

842.2 

1199.0 

2.241 

210 

385.87 

358.9 

840.7 

1199.6 

2.190 

215 

387.88 

361.0 

839.2 

1200.2 

2.142 

220 

389.84 

363.0 

837.8 

1200.8 

2.096 

225 

391.79 

365.1 

836.3 

1201.4 

2.051 

250 

400.99 

374.7 

829.5 

1204.2 

1.854 

275 

409.50 

383.6 

823.2 

1206.8 

1.691 

300 

417.42 

391.9 

817.4 

1209.3 

1.553 

325 

424.82 

399.6 

811.9 

1211.5 

1.437 

350 

431.90 

406.9 

806.8 

1213.7 

1.337 

375 

438.40 

414.2 

801.5 

1215.7 

1.250 

400 

445.15 

421.4 

796.3 

1217.7 

1.172 

500 

466.57 

444.3 

779.9 

1224.2 

.939 

ENGINE  NOTES. 

Steam  at  atmospheric  pressure  flows  into  a  Vacuum  at  the  rate 
of  about  1,550  feet  per  second,  and  into  the  Atmosphere  at  the  rate 
of  650  feet  per  second. 

The  specific  gravity  of  steam  (at  atmospheric  pressure)  is  .411, 
that  of  air  at  34  deg.  Fahrenheit,  and  .0006  that  of  water  at  same 
temperature. 


SELECTION  OF  BOILER.  31 

33000  minute  foot  pounds  equal  1  H.  P. 

396000  minute  inch  pounds  equal  1  H.  P. 

A  cubic  inch  of  water  evaporated  under  atmospheric  pressure  is 
approximately  converted  into  1  cubic  foot  of  steam. 

The  horse  power  of  boilers,  as  per  standard  adopted  by  the  Am. 
S.  M.  E.,  is  30  pounds  water  evaporated  per  hour  at  a  pressure  of  70 
pounds  per  square  inch  and  from  a  temperature  of  100  degrees 
Fahr. 

Well  designed  boilers,  under  successful  operation,  will  evaporate 
from  7  to  10  pounds  of  water  per  pound  of  first-class  coal. 

Each  square  foot  of  heating  surface  is  considered  sufficient  to 
evaporate  3*/>  pounds  of  water;  therefore,  for  an  engine  using  30 
pounds  of  water  per  horse  power  per  hour,  each  horse  power  of  the 
engine  reqttiresg.75square  feet  heating  surface  in  the  boiler. 

On  one  square  foot  of  fire  grate  can  be  burned  on  an  average 
from  10  to  12  pounds  hard  coal,  or  18  to  35  pounds  soft  coal,  per 
hour,  with  natural  draft. 

Two  and  one-quarter  pounds  of  dry  wood  is  equal  to  1  pound  of 
average  quality  soft  coal. 

Condensing  engines  require  from  20  to  30  times  the  amount  of 
feed  water  for  condensing  purposes;  approximately  for  most  en- 
gines, 1  to  \y2  gallons  condensing  water  per  minute  per  indicated 
horse  power,  -depending  on  temperature  of  injection  water. 

Surface  condensers  for  compound  steam  engines  require  about 
2  square  feet  of  cooling  surface  per  horse  power ;  ordinary  engines 
will  require  more  surface  according  to  their  economy  in  the  use  of 
steam.  It  is  absolutely  necessary  that  the  air  pump  should  be  set 
lower  than  the  condenser  for  satisfactory  results. 

The  effect  of  a  good  air  pump  and  condenser  should  be  to  get 
25  inches  of  vacuum  and  to  make  available  about  10  pounds  more 
mean  effective  pressure  with  the  same  terminal  pressure,  or  to  give 
the  same  mean  effective  pressure  with  a  correspondingly  less  ter- 
minal pressure.  Approximately,  a  good  condenser  will  save  one- 
fourth  of  the  fuel  consumed,  or,  in  other  words,  increase  the  power 
of  the  engine  one-fourth,  the  fuel  consumption  remaining  the  same. 

One  pound  of  water  evaporated  from,  and  at  212°  F.  is  equiv- 
alent to  965.7  British  thermal  units. 

The  evaporation  of  30  pounds  of  water  per  hour,  from  a  temper- 


32  THE  BOILER. 

ature  of  100°  F.,  into  steam  at  70  pounds  gauge  pressure  =  one 
H.  P.  This  is  equivalent  to  34^  pounds  of  water  from  and  at 
212°  F. 

A  common  rule  to  find  horse  power  on  an  engine :  Multiply  area 
of  piston  by  pressure  per  square  inch  and  by  length  of  stroke  and 
again  by  number  of  revolutions  per  minute;  divide  this  sum  by 
constant  16500. 

LEGEND:  FORMULA: 

P  =  pressure  =  100  Ibs.  A  X  P  X  S  X  R 

A  =  area  of  piston  =  7 8.  5 400  —  =H.P. 

S  =  length  of  stroke  in  feet  =  1  ft.  C 

R  =  number  of  revolutions  =  70 

C  =  constant  =  16500 

EXAMPLE: 

78 .  5400  =area  of  piston 
100=lbs.  pressure 


7854.0000 

1  ft.  stroke 


7854.0000 

70  =  number  of  revolutions 


constant  =  16500)  549780.0000  (33 . 3  = horse  power 
49500 


54780 
49500 

52800 
49500 


3300 


THE  THERMOMETER. 

To  convert  Fahrenheit  degrees  to  centigrade,  subtract  32  de- 
grees from  number  of  degrees  Fahrenheit;  multiply  the  sum  by  5 
and  divide  product  by  9. 

LEGEND:  FORMULA: 

F     =  Fahrenheit  =32°  5  X    (F— 32) 

C     =  Centigrade  =  100°  —  =  Centigrade 

R    =  Reaumur  =  80°  9 


SELECTION  OF  BOILER.  33 

EXAMPLE: 

212=degrees  Fahrenheit 
32 

180 
5  - 

9)900 

100=  Centigrade 

To  convert  Centigrade  degrees  to  Fahrenheit :  Multiply  the 
number  of  degrees  centigrade  by  9,  divide  result  by  5  and  add  32  to 
quotient. 

FORMULA:  EXAMPLE: 

9  X  C  100=  degrees  Centigrade 

-  +  32  =  Fahrenheit  9 

SJ  

5)900 

180 
32     to  be  added 

212  =  degrees  Fahrenheit 

To  convert  Fahrenheit  degrees  to  Reaumur  subtract  from  num- 
ber of  degrees  Fahrenheit  32;  multiply  result  by  4  and  divide 
product  by  9. 

FORMULA:  EXAMPLE: 

4  X   (F  —  32)  2 12=  degrees  Fahrenheit 

—  =  Reaumur                                     32 
g  

180 

4 

9)720 


80      =  degrees  Reaumur 

To  convert  Reaumur  degrees  to  Fahrenheit:  Multiply  number 
of  degrees  of  Reaumur  by  9;  divide  product  by  4  and  add  32  to 
quotient. 

FORMULA:  EXAMPLE: 

9  X  R  80=  degrees  Reaumur 

+  32  =  Fahrenheit  9 

4  

4)720 

180 
32     to  be  added 

212  =  degrees  Fahrenheit 


34 


THE  BOILER. 

COMPARISONS  OF  THERMOMETER  SCALES. 


Fahrenheit 

Centigrade 

Reaumur 

Fahrenheit 

Centigrade 

Reaumur 

—  4 

—20 

-16 

113 

45 

36 

+    5 

15 

12 

112 

50 

40 

14 

10 

8 

131 

55 

44 

23 

5 

4 

140 

60 

48 

32 

0 

0 

149 

65 

52 

41 

+    5 

+   4 

158 

70 

56 

50 

10 

8 

167 

75 

60 

59 

15 

12 

176 

80 

64 

68 

20 

16 

185 

85 

68 

77 

25 

20 

194 

90 

72 

86 

30 

24 

203 

95 

76 

95 

35 

28 

212 

100 

80 

104 

40 

32 

BOILING 

BOILING 

BOILING 

FREEZING 

FREEZING 

FREEZING 

POINT 

POINT 

POINT 

POINT 

POINT 

POINT 

212 

100 

80 

32 

0 

0 

CHAPTER  III. 

BOILER  CONSTRUCTION. 

Boiler  construction  can  be  classed  as  one  of  the  highest  among 
crafts.  In  old-time  boiler  making  holes  were  punched  leaving  in- 
itial fractures  around  edge  of  holes  and  often  times,  when  assem- 
bling joints,  holes  were  found  out  of  alignment,  and  to  admit  a 
rivet  the  plate  had  to  be  cut  by  reaming  to  make  the  holes  coincide, 
thus  reducing  the  percentage  of  strength,  at  best,  very  low.  Today 
drilled  holes  are  specified  by  reliable  authorities  and  followed  up  by 
reputable  boiler  makers.  Modern  machinery  of  today  has  developed 
a  wonderful  improvement  in  the  craft ;  it  has  taken  the  place  of  old- 
time  hand  methods ;  accuracy,  efficiency  and  strength  have  been 
gained ;  improved  tools  to  facilitate  work,  brain  and  not  all  muscle 
employed  by  the  mechanics ;  he  reasons,  conceives,  then  executes 
with  these  modern  conveniences ;  his  aim  is  to  produce  results,  bet- 
terment of  his  work.  Flanging  machines  have  added  factors  to 
safety ;  that  old  methods  of  flanging  were  not  conducive  to  good 
effects  or  results  is  now  apparent ;  for  when  the  part  of  work 
to  be  flanged  was  heated,  hammered,  reheated  and  hammered  again 
— hot  and  cold — often  resulting  in  defects  in  plates  that  made  them 
unfit  for  use,  time  and  material  would  be  wasted.  With  the 
modern  flanging  machine  time  is  saved,  expense  lessened  and  work 
turned  out  as  near  perfect  as  possible,  one  heat  and  the  cooling 
having  an  annealing  effect,  general  and  gradual,  gang  punches  ad- 
justed accurately,  time  and  labor  saved  and  the  efficiency  of  joint 
holes  not  impaired. 

Rivet  machinery  with  its  power  of  compression  ensures  strength 
of  rivet  joints  and  lessens  the  effect  of  injury  to  plate  by  caulking  as 
done  by  the  old-time  hand  riveted  joint,  especially  when  left  to  the 
novice,  defects  were  developed  and  material  operated  on  was  de- 
stroyed. 

Electric  cranes  and  air  lifts  are  found  necessary  for  facilitating 
work  by  aiding  in  assembling  or  fitting  up  parts  of  boilers  under 
construction. 

35 


36  THE  BOILER. 

Thus  we  find  boiler  making  today  one  of  the  scientific  mechanical 
crafts  and  with  the  expectations  that  work  carried  out  as  designed 
produce  the  best  results. 

This  book  will  give  general  rules  and  tables  used  in  the  construc- 
tion of  the  steam  boiler  and  governing  their  use  in  safety. 


RIVETS  AND  RIVETING. 

In  designing  a  joint  like  any  part  of  the  construction  of  boilers, 
care  in  calculation  and  proportioning  of  rivet  are  very  essential. 
Shearing  strength  and  ductility  are  important  factors;  perfect 
alignment  of  holes,  size  of  same,  and  method  of  making  same,  must 
not  be  overlooked. 

On  the  driving  of  a  rivet  will  depend  much.  Without  going  into 
the  details  on  the  subject  of  riveting  it  may  be  well  to  say  that  in  the 
old-time  methods  of  hand  riveting  the  structural  makeup  of  a  rivet 
was  changed ;  when  the  rivet  should  have  been  finished,  the  many 
repeated  blows  soon  changed  its  nature,  and,  unnecessary  to  say, 
"it  was  near  finished."  But  improved  machinery  has  wrought 
changes  and  with  it  the  changing  of  rivet  material — this  in  turn  has 
provided  a  larger  factor  of  safety  using  old  rules,  and  has  provided 
greater  efficiency  by  lighter  material. 

The  heating  of  rivet  to  proper  degree  of  heat  is  another  im- 
portant measure  and  with  modern  forges  as  used  this  can  be  ac- 
complished with  no  difficulty  or  more  than  ordinary  attention. 


BOILER  CONSTRUCTION. 


37 


TABLE   OF   RIVETS   AND   BOLTS   WITHOUT   NUTS   IN   100  LBS. 
Average    number. 


Length 
of 
Rivets. 

•  DIAMETER  OF  RIVETS. 

H 

A 

H 

A 

1A 

5A 

tt 

M 

K 

M 

8000 

5100 

3200 

1900 

5/8 

7000 

4500 

2900 

1800 

H 

6300 

4100 

2373 

1476 

1103 

642 

H 

5700 

3700 

2190 

1371 

1030 

604 

i 

5200 

3400 

2034 

1280 

968 

571 

400 

345 

IH 

4700 

3100 

1898 

1200 

910 

541 

382 

322 

208 

IH 

4400 

2900 

1780 

1129 

862 

514 

365 

311 

206 

IH 

4100 

2700 

1675 

1066 

815 

489 

350 

295 

204 

m 

4000 

2500 

1582 

1010 

776 

462 

335 

284 

201 

IS 

3800 

2300 

1498 

960 

740 

446 

324 

275 

199 

m 

3500 

2200 

1424 

914 

707 

428 

311 

266 

192 

IK 

3400 

2000 

1356 

872 

672 

411 

302 

257 

185 

2 

3000 

1900 

1295 

834 

648 

395 

293 

249 

178 

2y8 

1238 

800 

623 

381 

285 

240 

172 

2^4 

2800 

1800 

1187 

768 

599 

367 

277 

233 

167 

2Ys 

1139 

738 

577 

354 

269 

226 

162 

21A 

2500 

1700 

1095 

711 

556 

343 

261 

219 

157 

1% 

1052 

687 

537 

332 

253 

212 

152 

2% 

1017 

662 

519 

321 

245 

206 

148 

2y» 

982 

636 

503 

311 

237 

201 

144 

3  8 

.... 

.... 

949 

611 

487 

302 

230 

196 

140 

3^ 

890 

581 

459 

285 

218 

186 

132 

3^9 

837 

548 

433 

270 

208 

177 

126 

/^ 

3% 

791 

519 

411 

257 

198 

168 

120 

**  X4- 

3^ 

395 

250 

195 

165 

119 

'749 

"400 

390 

244 

189 

161 

115 

4K 

372 

233 

180 

155 

110 

4V4 

355 

223 

172 

149 

105 

4% 

339 

214 

166 

143 

101 

5 

« 

325 

205 

160 

136 

97 

5M 

312 

197 

154 

131 

94 

•^  /4r 

5U 

300 

190 

149 

127 

91 

5M 

289 

183 

144 

123 

88 

6 

279 

177 

139 

118 

85 

The    measurement   of    a   cone   or   button    head    rivet   is   taken 
under  the  head;  rivets  for  counter  sunk  holes  measured  over  all. 


38 


THE  BOILER. 


to  "\ 


BOILER  CONSTRUCTION. 


39 


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40 


THE  BOILER. 


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BOILER  CONSTRUCTION. 


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42 


THE  BOILER. 


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BOILER  CONSTRUCTION.  43 

ESTIMATING   THE   WEIGHT   OF    STEEL    PLATES. 

The  table  of  the  weight  of  steel  plates  is  based  upon  the  as- 
sumption that  one  cubic  inch  of  rolled  steel  weighs  .2833  pounds 
and  that  this  is  increased,  by  the  springage  of  the  rolls,  by  a  certain 
percentage  depending  upon  the  width  and  thickness  of  the  plate 
and  which  is  assumed  to  be  in  accordance  with  a  table  given  here- 
with : 


PERCENTAGE  OF  INCREASE  OF  DENSITY  OF  ROLLED  STEEL  PLATES. 


THICKNESS 
OF  PLATE. 

Inch. 

WIDTH  OF  PLATE. 

Up  to  75 
Inches. 
Per  cent. 

75  to  100 

Inches. 
Per  cent. 

100  to  115 
Inches. 
Per  cent. 

Over  115 
Inches. 
Per  cent. 

17 
13 
12 
11 
10 
9 

Over  y% 

10 

8 
7 
6 
5 

4 

14 

12 
10 
8 
7 

6  2 
5 

18 

16 
13 
10 
9 

8 

To  illustrate  the  method  used  in  calculating  the  table  fol- 
lowing this  article,  we  will  calculate  the  estimated  weight  of  a 
Y4"  plate  38"  wide  and  138"  long.  Multiplying  these  three 
dimensions  together  gives  us  the  number  of  cubic  inches  of 
steel  in  the  plate  as  follows:  J4  X  38  X  138=  1311.  As  the 
increase  in  density  is  10  per  cent  for  this  size  plate,  according 
to  the  table,  we  add  10  per  cent  to  the  weight  of  one  cubic 
inch  of  steel  (.2833)  as  follows:  .2833  X  .10  =  .02833  and 
.2833  +  .02833  =  .31163  —  the  weight  in  pounds  of  one  cubic 
inch  of  steel  in  this  particular  plate.  Multiplying  the  number 
of  cubic  inches  in  the  plate  (1311)  by  this  gives  us  the 
weight  of  the  plate  in  pounds  as  follows:  131 IX -31 16  = 
408.55  =  weight  of  plate  in  pounds.  Taking  the  nearest  unit 
makes  it  409,  which  agrees  with  the  table,  but  no  allowance  has 
been  made  here  for  springage  of  the  rolls  and  in  using  this  table 
the  percentage  given  in  the  table  above  must  be  added.  By  so  doing 
we  get  a  result  which  will  agree  very  closely  with  the  table. 


44  THE  BOILER. 

WEIGHT  PER  SQUARE  FOOT  OF  ROLLED  STEEL  PLATE  NOT  ALLOWING  FOR 
SPRINGAGE  OF  ROLLS. 

Thickness  of  Pounds  per  Thickness  of  Pounds  per 

Plate,  inches.  Sq.  Foot.  Plate,  inches  Sq.  Foot. 

y8 25.497 

& 1 . 2748  ft 28 .  047 

A 2.5496  % 30.596 

:& 3 .  8244  if 33  . 146 

y8 5.0992  y8 35.696 

£ 6.3740  ft 38.245 

^ 7.6488  1      40.795 

& 8.9236  1^ 43.344 

JJ 10.199  iy8 45.894 

& 11.474  1& 48.444 

& 12 .  749  I  & 50 . 993 

& 14.024  1& 53.543 

Y% 15.299  -IJj 56.092 

M 16.574  1^6 58.642 

A 17.849  1^ 61.192 

|| 19.124  l^C 71.390 

% 20.398  lJ/8 76.489 

A.                     ..22.948  2                          ..81.588 


The  weight  per  square  foot  of  l/^"  plate  as  given  by  this 
table  is  10.199  and  in  a  piece  of  38"  X  138",  according  to  the 
first  table,  the  increase  would  be  10  per  cent,  making  the  in- 
crease 10.199  X  -10  =  1.0199.  Adding  the  increase  to  the  weight 
per  square  foot  given  in  the  table  makes  it  11.2189  as  follows: 
10.199  +  1.0199  =  =  11.2189.  The  area  of  the  plate  in  square  feet 
is  obtained  by  multiplying  its  width  by  its  length  in  inches 
and  dividing  by  144  the  number  of  square  inches  in  a  square 
foot,  as  follows :  38  X  138  =  5244  =  number  of  square  inches  in 
plate.  Dividing  this  by  144  gives  us  the  arek  of  the  plate 
in  square  feet,  as  follows :  5244  4-  144  =  36.417  =  number  of 
square  feet  in  plate.  Multiplying  this  by  the  weight  per 
square  foot  as  calculated  above  (11.219)  gives  us  the  weight  of 
the  plate  as  follows:  36.417  X  11.219  =  408.56  =  weight  of  plate 
in  pounds.  This  agrees  practically  with  the  table  given  below 
and  the  weight  calculated  by  the  other  method  at  the  beginning 
of  this  article. 


BOILER  CONSTRUCTION. 


45 


WEIGHT  OF  STEEL  BOILER  PLATES. 


PLATE. 


Size.  Weight, 

Pounds. 

26X120 243 

26X138..'. 280 

30X120 280 

30X138 323 

36X120 «. 337 

36X138 387 

38X120 355 

38X138 409 

40X120 374 

40X138 .430 

40X143 446. 

42X120 393 

42X138 452 

43X138 462 

43X143 479 

43X156 523 

44X120 411 

44X138 473 

46X120 430 

46X138 495 

48X120 449 

48X138 516 

49X  98 374 

49X138 552 

49X143 572 

49X156 624 

50X120 467 


Size. 


Weight, 
Pounds. 

50   X138 538 

54   X120 505 

57   X138 613 

57   X143 635 

57   X156 693 

60   X  98 458 

60   X120 561 

60   X138 645 

64%X138 696 

64%  X  143 721 

64%X156 787 

64%  X  175 883 

64%  X  194 979 

72   X  98 550 

72   X120 673 

72   X138 774 

72   X143 802 

72   X156 875 

72   x'175 982 

72   X194 1088 

84   x  98 665 

84   X120 814 

84   X138 936 

84   X143 970 

84   X156 .1058 

84   X175 :1187 

84   X194..          ..1316 


PLATE. 


26  X  80 199 

26  X  90 223 

26  X  99 246 

26X120 298 

26X138 ...343 

30  X  80 229 

30  X  90 258 

30  X  99 284 

30X120 344 

30X138 396 

36  X  80 275 

36X  90 310 

36X  99 341 

36X120 413 

36X138 475 

38X  80 291 

38  X  90 327 

38X  99 360 

38X120 435 

38X138 501 

40X  80 306 

40  X  90 344 

40X  99..  ..379 


49   X143 670 

49   X156 731 

49   X175 820 

49  X194 909 

50  X120 574 

50   X138 660 

54   X120 620 

57   X  80 436 

57   X  90 490 

57   X  99 540 

57   X138 752 

57   X143 779 

57  X156 850 

57   X175 954 

57   X194 1057 

60   X120 688 

60   X138 792 

64%X  90 557 

64%  X  99 613 

64%  X 138 854 

64%X143 885 

64%X156 966 

64%X175 1083 


46 


THE  BOILER. 


PLATE. 


Size. 

40X120 

40X138 

42X120 

42X138 

43 X  80 

43  X  90 

43 X  99 

43X138 


Weight, 
Pounds. 
. .. .459 
....528 

482 

554 

329 

370 

407 

.-...567 


Size. 

64 ''4X194. 
72^,X  99. 
72^X120. 
72^X138. 
72^X143. 
72^X156. 
72^X175. 
72^X194. 


Weight, 

Pounds. 

1201 

686 

832 

957 

991 

1081 

1213 

1345 


PLATE. 


30      X120 499 

36      X120  491 

36      X138  565 

40      X120  546 

40      X138  627 

44      X120  600 

44      X138  690 

48      X120  655 

48      X138  753 

50      X120  682 

50      X138  784 

54      X120  737 

54      X138  847 

60      X120  818 

60      X138  941 

64^X118  869 

64MX194  1428 

64^X212^ 1564 

64^X231^ 1704 

65MX108J4 799 


72^X108^  ............    894 

72^X118  ..............    972 

72^X212^  ............  1751 

72^X231^  ............  1908 

84 
84 
84 
84 
84 
96 
96 
96 
96 
96 


X118 
X194 


1065 
1158 
1904 
2086 
2282 
1217 
1324 
2176 
2384 
2597 
107^X108^  ............  1400 

107^X118   '  ............  1523 

107^X194      ............  3504 

107^X212^  ............  2742 

107^X231^  ............  2988 


XH8 

X194 


36X120. 
40X120. 
48X120. 


568 
631 

757 


PLATE. 


60X120 946 

72X120..          1135 


36X120 643 

40X120 714 

48X120..  .  857 


PLATE. 


60X120 1071 

72X120 1285 


36X120 950 

40X120 ...1056 

48X120..  ..1267 


PLATE. 


60X120 1583 

72X120..  ..1900 


40X112   1149 

40X154^.... 1996 

53X112 1523 


PLATE. 


53X133 1809 

53X154 2094 


BOILER  CONSTRUCTION. 


47 


TABLES  OF  WIDTH,  LENGTH  AND  THICKNESS  OF  PLATES  THAT  CAN  BE  MADE 
FOR  BOILER  PURPOSES,  ALSO  DIAMETER  OF  HEADS. 


Thickness. 

Diameter  of 
Heads. 

Width  and  Length  of  Plate. 

Width. 

Length. 

1A 
A 

1 

y* 

5/s 

115 
120 
126 
126 
126 
126 

114' 
126' 
140' 
140' 
144' 
144' 

200' 
240' 
180' 
180' 
180' 
180' 

Longer  lengths  can  be  made  but  would  be  less  in  width. 


Rules  adopted  by  the  Association  of  American  Steel  Manu- 
facturers:  "When  ordering  plates  \2l/2  pounds  to  square  footer 
heavier,  up  to  100  inches  wide,  by  weight,  they  shall  not  average 
more  than  2l/2  per  cent  above  or  below  the  theoretical  weight,  when 
100  inches  and  over  the  limit  is  5  per  cent." 


TABLE   OF  ALLOWANCES   FOR  OVERWEIGHT   FOR  RECTANGULAR  PLATE 
WHEN  ORDERED  BY  GAUGE. 


Thickness 
of 
Plate. 

WIDTH   OF  PLATE. 

Up  to 
50  inches. 

50  inches 
and  above. 

Up  to 
75  inches. 

75  inches 
to  100  in. 

over  100 

inches. 

y%  up  to  -3% 

&  up  to  ^ 

T\  UP  to  y± 
A- 

1 

I 

y% 

over    *A 

10  per  ct. 

SK  ;;  ;; 

15  per  ct. 

12^"   " 
10     "   " 

10    p< 

8 
7 
6 
5 
4^ 
4 
ZVo 

;r  c 

t. 

14    p( 
12 
10 
8 
7 
6^ 
6 
5 

jr  c 

t. 

18     p 
16 
13 
10 
9 
8^ 
8 
6K 

er  ct 

48 


THE  BOILER. 
DOME  PLATE  ALLOWANCES. 


Diame- 

DIAMETER OF  SHELLS. 

ter  of 

Domes. 

30 

36 

42 

48 

54 

60 

66 

72 

84 

20 

6K 

ST/ 

5  K 

22 

7  if 

6}/ 

5% 

5  V 

24 

gi/ 

7  */ 

5% 

5  1/ 

26 

g{/ 

7  1/  ' 

6 

28 

9^/ 

8 

7% 

6 

30 

10% 

9 

8 

7% 

6% 

6% 

5% 

5% 

32 

10 

8% 

8 

7% 

6% 

6% 

5% 

34 

.  .  . 

9% 

8% 

8 

7M 

7 

6 

36 

.  .  . 

10% 

93^ 

8/^ 

8 

7% 

6;Hj 

38 

10% 

9/^ 

8% 

8 

7 

40 

10M 

9% 

71^ 

42 

11  M 

10% 

10 

8 

44 

11 

10  Vo 

9 

46 

12% 

10% 

9^ 

48 

13 

11^ 

10 

The  above  table  is  based  on  single  riveting,  and  the  allowances  named 
are  those  commonly  used  in  figuring  the  finished  length  of  domes.  For 
double  riveting  add  2  inches. 


BOILER  CONSTRUCTION. 


49 


m 


<  X 

7.  D 

«c/2 

H 

X 

W 


CSdlS 

3^ 


Iffi 

0^  C/} 


s  1 


—•  o 

a  "-^ 

c  o 

i>  C8 

"S  3 

-  cK 


5      « 

«  i 


£    J3 

^       o 


•^  o 

'i  E  "5 

HH    W  C 

Q 


vO  N  OO  t^  O\ 


VO  i-H  t^  VO  VO  OO  rH 


OO>—  1  i—  li—  t 


»H\ 


50 


THE  BOILER. 


Rule  to  find  number  of  square  feet  of  heating'  surface  in  tubes : 
Multiply  the   number   of   tubes   by   the   diameter   of   a   tube   in 
inches  and  by  its  length  in  feet,  and  by  .2618  constant. 


LEGEND: 

D=Tubes  4" 
L=  Length  =16' 
N=  Number  =  44 
C=  Constant  =  .26 18 


FORMULA: 
N  XDxLx  .2618  (constant)  =heating  surface 


EXAMPLE: 

44  =  number  of  tubes 
4  =  diameter  in  inches 

176 

16  =  length  in  feet 


1056 
176 

2816 

261 8=  constant 


22528 
2816 

16896 

5632 


737.2288  =total  square  feet  of  heating  sur- 
face in  44  4"  tubes. 


HEATING  SURFACE  OF  BOILER  TUBES. 

Diameter  X  3.1416  =  circumference  X  12  =  number  of  square 
inches  in  tube  one  foot  of  length  -=-  144  =  number  of  square  feet 
(in  decimals)  one  foot  of  length. 


EXAMPLE: 

2  inch  tube  one  foot  in  length : 
2X3. 1416  =6 . 2832  X  12  =  75  . 3984 

—  =  .  5236  of  a  square  foot 
144 


BOILER  CONSTRUCTION. 


51 


TABLE. 


Diam. 

Diam. 

Diam. 

Diam. 

in. 

Multipl'r 

in. 

Multipl'r 

in. 

Multipl'r 

in. 

Multipl'r 

1 

.2618 

11^ 

3.0107 

|   32 

8.3776 

53 

13.8754 

1M 

.3272 

H« 

3.0761 

32^ 

8.5085 

53^ 

14.0063 

1H 

.3927 

12 

3.1416 

33 

8.6394 

54 

14.1372 

134 

.4581 

12^ 

3.2725 

33  H 

8.7703 

54^ 

14.2681 

2 

.5236 

13 

3.4037 

34 

8.9012 

55 

14.399 

2M 

.589 

U% 

3.5343 

34^ 

9.0321 

55^ 

14.5299 

2K 

.6545 

14 

3.6652 

35 

9.163 

56 

14.6608 

2M 

.7199 

14^ 

3.7961 

35^ 

9.2939 

56^ 

14.7917 

3 

.7854 

15 

3.927 

36 

9.4248 

57 

14.9226 

34 

.8508 

15^ 

4.0579 

36^ 

9.5557 

57^ 

15.0536 

3^ 

.9163 

16 

4.1888 

37 

9.6866 

58 

15.1844 

3i4 

.9817 

16^ 

4.3197 

37^ 

9.8175 

58^ 

15.3153 

4 

1.0472 

17 

4.4506 

38 

9.9844 

59 

15.4462 

4M 

1.1126 

17^ 

4.5815 

38^ 

10.0793 

59^ 

15.5771 

4H 

1.1781 

18 

4.7124 

39 

10.2102 

60 

15.708 

4%      |    1.2435 

18H 

4.8433 

39^ 

10.3411 

60^ 

15.8389 

5 

1.309 

19 

4.9742 

40 

10.472 

61 

15.9698 

5M 

1.3744 

19^ 

5.1051 

40^ 

10.6029 

61^ 

16.1007 

5H 

1.4399 

20 

5.236 

41 

10.7338 

62 

16.2316 

5M 

1.5053 

20^ 

5.3669 

41^ 

10.8647 

62^ 

16.3625 

6 

1.5708 

21 

5.4978 

42 

10.9956 

63 

16.4934 

64 

1.6362 

21^ 

5.6287 

42  Y2 

11.1265 

63^ 

16.6243 

6^ 

1.7017 

22 

5.7596 

43 

11.2574 

64 

16.7552 

6-M 

1.7671 

22^ 

5.8905 

43^ 

11.3883 

64  H 

16.8861 

7 

1.8326 

23 

6.0214 

44 

11.5192 

65 

17.017 

7K 

1.8980 

23^ 

6.1523 

44^ 

11.6501 

65^ 

17.1479 

7^ 

1.9335 

24 

6.2832 

45 

11.781 

66 

17.2788 

7*4 

2.0289 

24^ 

6.4141 

45^ 

11.9119 

66^ 

17.4097 

8 

2.0944 

25 

6.545 

46 

12.0428 

67 

17.5406 

8M 

2.0598 

25^ 

6.6759 

46^ 

12.1735 

67^ 

17.6715 

8H 

2.2253 

26 

6.8034 

47 

12.3045 

68 

17.8024 

8-M 

2.2907 

26^ 

6.9377 

47^ 

12.4355 

68^ 

17.9333 

9 

2.3562 

27 

7.0686 

48 

12.5664 

69 

18.0642 

9M 

2.4216 

27^ 

7.1995 

48^ 

12.6973 

69^ 

18.1951 

9^ 

2.4872 

28 

7.3384 

49 

12.8282 

70 

18.326 

94 

2.5525 

28^ 

7.4614 

49  H 

12.9591 

70^ 

18.4569 

10 

2.618 

29 

7.5913 

50 

13.09 

71 

18.5868 

iOM 

2.6834 

29^ 

7.7231 

50^ 

13.2209 

71^ 

18.7187 

ion 

2.7489 

30 

7.8554 

51 

13.3518 

72 

18.8496 

IOM 

2.8143 

30^ 

7.9849 

51^ 

13.4827 

78 

20.3370 

11 

2.8798 

31 

8.1158 

52 

13.6136 

84 

21.9912 

HM 

2.9452 

31H 

8.2467 

52^ 

13.7445 

96 

25.1328 

52 


THE  BOILER. 


APPROXIMATE  WEIGHT  OF  ROUND  BRACES  WITH  FLAT  ENDS. 


Length  of 
Braces,  inches 

Diameter  of 
Braces,   inches 

SIZE  OF  ENDS. 

Weight, 
Ibs. 

Width,  inches 

Thickness,  in. 

14 

1 

2M 

)4 

7 

16 

1 

2M 

y* 

7M 

18 

1 

2^ 

y* 

7)4 

20 

1 

y* 

8 

22 

1 

2^ 

y* 

&)4 

24 

1 

y* 

9 

26 

1 

P 

y* 

9y> 

28 

1 

)4 

10 

30 

1 

2  M 

H 

10/^ 

32 

1 

2M 

¥ 

11 

34 

1 

2M 

111^ 

36 

1 

2M 

i^ 

12 

38 

1 

Ip 

'^ 

12^ 

40 

1 

/^ 

13 

42 

1 

2M 

Yt 

13J^ 

44 

1 

y^ 

14 

46 

1 

2M 

y% 

143^ 

48 

1 

2M 

% 

15 

50 

1 

2M 

x^ 

15/^9 

52 

1 

2M 

/^2 

16 

54 

1 

2M 

1 

16)4 

56 

1 

17 

58 

1 

2M 

^ 

173^ 

60 

1 

2M 

x^ 

18 

14 

1  /^ 

5^ 

7)4 

16 

1^8 

2M 

% 

8 

18 

l//g 

2M 

Y% 

8/^2 

20 

\^/Q 

% 

9 

22 

l/"8 

2M 

% 

10 

24 

1^8 

2M 

% 

11 

26 

\y% 

2^ 

5/8 

12 

28 

\y> 

%> 

13 

30 

\y 

2M 

H 

14 

32 

\y 

2M 

15 

34 

\V& 

2M 

sh 

16 

36 

\y^ 

2M 

/R 

17 

38 

1  ^ 

2/4 

% 

17/^2 

40 

\y% 

2M 

y% 

18 

42 

\y. 

2/^ 

% 

is  y^ 

44 

\y% 

2K 

% 

19 

46 

\y. 

2/4 

% 

19^ 

48 

1)4 

2M 

5/8 

20  f 

50 

1  ^8 

5/8 

21 

52 

\~\/ 

2M 

5/8 

22 

54 

\y^ 

2M 

5/8 

23 

56 

\y^ 

2M 

5/8 

24 

58 

ITX 

5/8 

25 

60 

1)4 

2M 

5/8 

26 

BOILER  CONSTRUCTION. 


53 


NUMBER  MODERN  FORMED  BRACES  COMMONLY  USED  IN  STANDARD  TUBULAR 

BOILERS. 


Length 
of 
Brace. 

DIAMETER  OF  SHELL. 

36 

42 

44 

54 

60 

66 

72 

84 

30 

42 
48 
60 
72 

6 

2 

6 

4 

8 

'4 

10 
'6 

10 

'6 

4 

10 
8 

'4 

12 

'k 

'4 

16 
16 
'6 

Under  the  diameter  of  each  shell  will  be  found  the  number  of  each 
length  of  brace  generally  used.  The  thickness  of  brace  varies  with  thickness 
of  shell. 


METALS. 
WEIGHT  OF  SUPERFICIAL  FOOT. 


Thick- 

ness. 

W  Iron. 

C  Iron. 

Steel. 

Copper. 

Brass. 

Lead. 

Zinc. 

Inch. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

TV 

2.52 

2.34 

2.55 

2.89 

2.73 

3.71 

2.34 

ys 

5.05 

4.69 

5.10 

5.78 

5.47 

7.42 

4.69 

& 

7.58 

7.03 

7.66 

8.67 

8.20 

11.13 

7.03 

x 

10.10 

9.38 

10.21 

11.56 

10.94 

14.83 

9.38 

A 

12.63 

11.72 

12.76 

14.45 

13.67 

18.54 

11.72 

y% 

15.16 

14.06 

15.31 

17.34 

16.41 

22.25 

14.06 

A 

17.68 

16.41 

17.87 

20  23 

19.14 

25.96 

16.41 

H 

20.21 

18.75 

20.42 

23   13 

21.88 

29.67 

18.75 

5/8 

25.27 

23  44 

25.52 

28.91 

27.34 

37.08 

23.44 

Y* 

30.31 

28.13 

30.63 

34.69 

32.81 

44.50 

28.13 

K 

35.37 

32.81 

35.73 

40.47 

38.28 

51.92 

32.81 

l 

40.42 

37.50 

40.83 

46.25 

43.75 

59.33 

37.50 

54 


THE  BOILER. 


BIRMINGHAM  GAUGE. 

U.  S.  STANDARD  GAUGE. 

No.  of 
Gauge. 

Thick- 
ness, 
Inches. 

Weight. 

No.  of 
Gauge. 

THICKNESS,   IN. 

Weight, 
Iron. 

Iron. 

Steel. 

Frac- 
tions. 

Deci- 
mals. 

0000 

.454 

18,22 

18.46 

0000000 

/v 

.5 

20. 

000 

.425 

17.05 

17.28 

000000 

i 

.468 

18.75 

00 

.38 

15.25 

15.45 

00000 

T6 

.437 

17.50 

0 

.34 

13.64 

13.82 

0000 

H 

.406 

16.25 

1 

.3 

12.04 

12.20 

000 

3'8 

.375 

15. 

2 
3 

.284 
.259 

11.40 
10.39 

11.55 
10.53 

00 

0 

1 

.343 
.312 

13.75 
12.50 

4 

.238 

9.55 

9.68 

1 

A 

.281 

11.25 

5 

.22 

8.83 

8.95 

2 

tt 

.265 

10.625 

6 

.203 

8.15 

8.25 

3 

X 

.25 

10. 

7 

.18 

7.22 

7.32 

4 

.234 

9.375 

8 

.165 

6.62 

6.71 

5 

Jy 

.218 

8.75 

9 

.148 

5.94 

6.02 

6 

£t 

.203 

8.125 

10 

.134 

5.38 

5.45 

7 

T¥ 

.187 

7.5 

11 

.12 

4.82 

4.88 

8 

M 

.171 

6.875 

12 

.109 

4.37 

4.43 

9 

A 

.156 

6.25 

13 

.095 

3.81 

3.86 

10 

* 

.140 

5.625 

14 

.083 

3.33 

3.37 

11 

.125 

5. 

15 

.072 

2.89 

2.93 

12 

Ft 

.109 

4.375 

16 

.065 

2.61 

2.64 

13 

$2 

.093 

3.75 

17 

.058 

2.33 

2.36 

14    1        A 

.078 

3.125 

18 

.049 

1.97 

1.99 

15 

llj^ 

.070 

2.8125 

19 

.042 

1.69 

1.71 

16 

.062 

2.5 

20 

.035 

1.40 

1.42 

17 

iftf 

.056 

2.25 

21 

.032 

1.28 

1.30 

18 

jfa 

.05 

2. 

22 

.028 

1.12 

1.14 

19 

_i 

.043 

1.75 

23 

.025 

1.00 

1.02 

20 

¥\ 

.037 

1.50 

24 

.022 

.883 

.895 

21 

VsV 

.034 

1.375 

25 

.02 

.803 

.813 

22 

T2 

.031 

1.25 

26 

.018 

.722 

.732 

23 

T*0 

.028 

1.125 

27 

.016 

.642 

.651 

24 

& 

.025 

1. 

28 

.014 

.562 

.569 

25 

ifao 

.021 

.875 

26 

_JL 

018 

.  75 

27 
28 

1^0 

S 

[017 

.015 

^6875 
.625 

The  U.   S.   Standard  is  the  one  in  common  use. 


To    CONVERT  WEIGHT  OF  METALS  MULTIPLY  BY    FOLLOWING  CONSTANTS: 

Wrought  iron  into  cast  iron X  -928 

"  steel X  1.014 

"  zinc X  -918 

"  brass X  1.082 

"  copper X  1.144 

"  "  lead XI.  468 

Square  iron  into  round • X  •  7854 


BOILER  CONSTRUCTION. 
WEIGHT  OF  CAST  IRON  BALLS. 


55 


DIAMETER. 

WEIGHT. 

DIAMETER. 

WEIGHT. 

DIAMETER. 

WEIGHT. 

1 
1H 

.136 
.460 

5 

5^ 

17.04 
22.68 

9 

9^ 

99.40 
116.90 

2 

1.09 

6 

29.45 

10 

136.35 

2^ 

2.13 

63^ 

37.44 

10^ 

157.84 

3 

3.68 

7 

46.76 

11 

181.48 

3^ 

5.84 

7^ 

57.52 

11^ 

207.37 

4 

8.72 

8 

69.81 

12 

235.62 

4^ 

12.42 

8]jj 

83.73 

ANGLES. 

WEIGHTS  PER  FOOT,  CORRESPONDING  TO  THICKNESS  VARYING  BY  -fa  INCH,  ONE  CUBIC  FOOT 

WEIGHING  480  LBS. 


Sizes, 
inches. 

« 

A 

X 

A 

H 

A 

H 

A 

% 

H 

H 

H 

H 

Equal 
Legs. 

6      x6 
5      x5 
4      x4 

3^x3^ 

3Mx3M 
3      x3 
2«£x2% 

2  J^  x  2  .^ 

2^x2^ 
2      x2 
1  M  x  1  % 
IMxlX 

\K*lX 

1         X  1 

&x     M 

16.75 
14.28 
11.16 
9.75 

9.05 
8.51 
7.70 
7.00 

6.29 
5.60 
5.00 

19.14 
16.56 
12.82 
11.20 

10.40 
9.74 
8.80 
8.00 

7.20 

21.53 
18.84 
14.49 
12.65 

11.75 
10.97 

23.92 
21.13 
16.16 
14.10 

13.10 
12.20 

26.31 
23.42 
17.83 
15.55 

14.45 

28.70 
25.71 
19.20 
17.00 

15.80 

31.10 
26.85 

33.50 
28.00 

12.00 
9.50 
8.30 

7.70 
7.28 
6.60 
6.00 

5.38 
4.80 
4.28 
3.60 

's.'io 

2.90 
2.60 
2.40 
2.20 

2.00 
1.66 
1.45 
1.23 

1.02 
.79 

.60 

'4.50 

4.20 

3.80 
3.50 
3.00 

2.80 
2.42 
2.13 
1.80 

1.50 
1.20 
.90 

'h'.QO 

8.66 
6.95 



4.83 
4.41 
4.00 

3.57 
3.21 
2.84 
2.40 

2.00 

6.05 
5.50 
5.00 

4.47 

4.00 
3.56 
3.00 

Unequal 
Legs. 

6      x4 
6      x3^ 
5      x4 
5      x3^ 

5      x3 
4      X3J4 
4      x3 

3.^x2% 

3^x3 
3^x2H 
3      x  2  >£ 
3^x2 

3      x2 

2^x2 
2       xl^ 

12.00 
11.50 
10.80 
10.20 

9.50 
8.90 
8.30 
7.50 

7.70 
7.30 
6.70 
6.37 

5.88 
4.92 

14.44 
13.24 
12.61 
11.26 

11.16 
10.46 
9.75 

8.75 

9.05 
8.55 
7.85 
7.43 

6.84 
5.66 

16.38 
14.98 
14.42 
13.72 

12.82 
12.02 
11.20 
10.00 

10.40 
9.80 
8.80 
8.50 

7.80 
6.40 

18.32 
16.72 
16.24 
15.49 

14.49 
13.59 
12.65 
11.25 

11.75 

20.26 
18.47 
18.06 
17.26 

16.16 
15.16 
14.10 
12.50 

13.00 

22.20 
20.22 
19.88 
19.03 

17.83 
16.73 
15.55 
13.75 

24.15 
21.97 
21.70 
20.40 

19.50 
18.30 
17.00 
15.00 

26.10 
23.72 
23.45 

28.00 
26.60 
25.20 





'.'.','.'. 





6.50 
6.05 
5.55 
5.31 

4.93 
4.18 

4.80 
4.40 
4.20 

3.98 
3.45 
2.90 



3.03 

2.72 
2.20 









56 


THE  BOILER. 
WEIGHTS  AND  MEASUREMENTS  OF  STEEL  "I"  BEAMS. 


Depth, 
Inches. 

Min. 
Weight, 
Ibs. 
per  foot. 

Inner  Weights. 

Max. 

Weight, 
Ibs. 
per  foot. 

Min. 
Flange, 
inches. 

Min. 
Web, 
inches. 

Min. 
Area, 
square 
inches. 

4 

7  5 

Vary  by  1  Ib 

10  5 

2   66 

19 

2  2 

5 
6 

9.75 
12  25 

Vary  by  2^  Ibs  
Vary  by  2U  Ibs.  . 

14.75 
17.25 

3.00 
3  33 

.21 
.23 

2.9 
3  6 

7 

15  0 

Vary  by  2^  Ibs  

20.0 

3  66 

.25 

4  4 

8 

17  75 

Vary  by  2^  Ibs  

25.25 

4.00 

.27 

5   2 

9 
10 

21.0 
25.0 

25  Ibs.  then  vary  by  5  Ibs. 
Vary  by  5  Ibs  

35.0 
40.0 

4.33 
4.66 

.29 
.31 

6.3 

7.4 

12 
12 

31.5 
40  0 

35  Ibs.  then  vary  by  5  Ibs. 
Vary  by  5  Ibs 

45.0 
55  0 

5.00 
5  25 

.35 

41 

9.3 

11  85 

15 
15 

42.0 
60.0 

45  Ibs.  then  vary  by  5  Ibs. 
Varv  bv  5  Ibs  .  .' 

60.0 
80.0 

5.50 
6.00 

.46 
.59 

12.5 
17.68 

WEIGHTS  AND  MEASUREMENTS  OF  STEEL  CHANNELS. 


Depth, 
Inches. 

Min. 
Weight, 
Ibs. 
per  foot. 

Inner  Weights. 

Max. 

Weight, 
Ibs. 
per  fool. 

Min. 
Flange, 
inches. 

Min. 
Web, 
inches. 

Min. 
Area, 
square 
inches. 

4 

5   25 

Vary  by  1  Ib  

7.25 

1.58 

.18 

1.6 

5 

6   5 

Varv  by  2^£  Ibs  

11.5 

1.75 

.19 

2.0 

6 

8  0 

Vary  by  2  y>  Ibs 

15  5 

1  92 

20 

2.4 

7 

9  75 

Vary  by  2  y>  Ibs 

19  75 

2  09 

.21 

2.9 

8 

11  25 

Vary  by  2^  Ibs 

21  25 

2  26 

.22 

3.4 

9 
10 

13^25 
15  0 

15  Ibs.  then  vary  by  5  Ibs. 
Vary  by  5  Ibs 

25.0 
35  0 

2.43 
2.60 

.23 
.24 

3.9 
4.5 

12 
15 

20.5 
33.0 

25  Ibs.  then  vary  by  5  Ibs. 
33  Ibs.  then  vary  by  5  Ibs. 

40.0 
55.0 

2.94 
3.40 

.28 
.40 

6.0 
9.9 

PIPE   AND    PIPING. 

Rule  to  find  pressure  allowed  on  a  main  steam  pipe  or  header 
when  thickness  of  pipe  and  diameter  is  known:  From  thickness 
of  plate  subtract  the  constant  .1250,  then  multiply  by  one-sixth  of 
tensile  strength  of  plate  and  divide  this  product  by  diameter;  the 
sum  will  be  pressure  allowed. 


LEGEND: 

T      =  Thickness  of  plate  =  .  4850 
C      =  Constant  =.1250 

T.  S  =  Tensile  strength     =  60000 
D     =  Diameter  =24" 


FORMULA  : 
(T— .  1250)  X  ( l/6th  of  TS) 


=  pressure 


BOILER  CONSTRUCTION.  57 


EXAMPLE: 

.4850  =  thickness  of  plate 
.1250=  constant 


.3600 

10000  =  1/6  of  tensile  strength 

diameter  24") 3600. 0000(150  Ibs.  pressure  allowed 
24 

120 
120 


Rule  to  find  thickness  of  material  for  a  main,  steel  or  iron, 
steam  pipe  or  cylinder  lap  welded:  Multiply  pressure  by  diameter 
and  divide  by  one-sixth  of  the  tensile  strength,  and  add  .125 

LEGEND.  FORMULA: 

P=  pressure  =  150  Ibs.  PXD 

D  =  diameter  =  24"  \-.  125  =thickness 

T.S.  = tensile  strength  =  60,000  1/6  of  T.  S. 

EXAMPLE: 

150    =lbs.  pressure 
24"=  diameter 


600 
300 


1/6  of  tensile  strength  =  10, 000)  3600  00(  .36 

3000  0      . 125  added 


600  00    . 485  =thickness  or  31/64 

600  00  approximately 


Rule  to  find  thickness  of  plate  for  a  5"  copper  pipe  :  Multiply 
pressure  by  inside  diameter  of  pipe  and  divide  by  constant  8000; 
add  to  quotient  the  constant  .0625. 

LEGEND:  FORMULA: 

P=  pressure  =  175  PXlD 

I D  =inside  diameter  of  pipe  =  .  5 f- .  062  5  =  thickness  of  plate 

C  =  constant  =  8000  C 

EXAMPLE: 
175    =pressure 
.  S"  =iriside  diameter  of  pipe 

8000) 87. 50000 (.109 

80  00          .062  5=  constant 


75  00       .  1 7 1 5  =  ££ approximately 
72  00 

3  00 


58 


THE  BOILER. 


RADIATION    OF    DIFFERENT    SIZES     OF    WROUGHT- 

IRON    PIPE. 

The  following  table  gives  the  actual  lengths  of  different  sizes 
of  pipe  sufficient  to  make  ten  square  feet  of  radiation : 

1      inch  Pipe,  28  lineal  feet  =  10  square  feet  radiation. 


i 

24 

"     =10 

.     ' 

20 

"     =10 

* 

16 

"     =10 

-' 

13 

"     =10 

« 

11 

"     =10 

TABLE  OF  EXPANSION  OF  WROUGHT-!RON  PIPE. 


Temperature 
of  the  Air 
when  the  Pipe 
is  fitted. 

Length  of 
Pipe 
when  fitted. 

LENGTH  OF  PIPE  WHEN  HEATED  TO 

160  Degrees. 

180  Degrees. 

200  Degrees. 

Degrees  Fahr. 

Feet. 

Feet. 

Inches. 

Feet 

Inches 

Feet 

Inches 

0 
32 
64 

100 
100 
100 

100 
100 
100 

1.28 
1.02 
.77 

100 
100 
100 

1.44 
1.18 
.93 

100 
100 
100 

1.60 
1.34 
1.09 

STANDARD  FLANGES.     SIZES:     THREADED  OR  PLAIN. 


Size  Pipe, 
Inches. 

Diameter 
Flange. 

Thickness 
of  Flanges. 

Equivalent 
to  Cast  Iron. 

1-       Inch 

6-       Inch 

2^-  Inch 

1^-Inch 

1  L/ 

6 

3^ 

ii4 

i'H 

6 

jl 

11^ 

2 

8 

1^ 

2 

21^ 

9 

^ 

2 

3 

9 

H 

2 

3^3 

10 

H 

2 

4 

10 

2 

4^3 

lO^j 

/^ 

2 

5 

11^ 

Ni 

2 

6 

WH 

^ 

2 

7 

133^ 

g 

2 

8 

15^ 

2^ 

9 

16^ 

'•  -:    ?J 

10 

17^ 

2M 

12 

21 

N 

2K 

BOILER  CONSTRUCTION. 


59 


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60 


THE  BOILER. 


TABLE  GIVING  DIAMETER  AND  AREA  AT  THE  BOTTOM  OF  THE  THREAD  OF 

STAY-BOLTS  AND  STAYS  OF  USEFUL  SIZES  FOR  CALCULATING 

THEIR  STRENGTH,  ETC. 


Diam. 
of  Stay 
Bolt 

Thread 
per  inch 

Diam.  at 
bottom  of 
thread 
U.  S. 

Area  in  sq. 
inches  at 
bottom  of 
thread 

UQ 

Diam.  at 
bottom  of 
thread 
V 

Area  in  sq. 
inches  at 
bottom  of 
thread 

y 

Standard 

.  o. 
Standard 

thread 

thread 

H 

12 

.51675 

.2097 

.48067 

.1815 

H 

12 

.57925 

.2635 

.54317 

.2317 

H 

12 

.64175 

.3235 

.60567 

.2881 

T§ 

12 

.  70425 

.3895 

.66817 

.3506 

1 

12 

.76675 

.4617 

.73067 

.4193 

it 

12 

.82925 

.5409 

.79317 

.4941 

1 

12 

.89175 

.6246 

.85567 

.5750 

1A 

12 

.95425 

.7152 

.91817 

.6621 

iH 

12 

1.01675 

.8119 

.98067 

.7553 

iA 

12 

1.07925 

.9148 

1.04317 

.8547 

\U 

12 

1.14175 

1.0238 

1.10567 

.9601 

1  ~fs 

12 

1.20425 

1.1390 

1.16817 

1.0718 

1% 

12 

1.26675 

1.2603 

1.23067 

1.1895 

1^ 

12 

1.39175 

1.5213 

1.35567 

1.4434 

6 

1.28350 

1.2939 

1.21134 

1.1525 

1% 

5^ 

1.38882 

1.5149 

1.31010 

1.3480 

\y± 

5 

1.49020 

1.7441 

1.40350 

1.5471 

!7/8 

5 

1.61520 

2.0490 

1.52850 

1.8349 

2 

4^ 

1.71134 

2.3001 

1.61512 

2.0487 

2l/8 

4^ 

1.83634 

2.6485 

1.74012 

2.3782 

2^ 

4^ 

1.96134 

3.0213 

1.86512 

2.7321 

2^ 

4 

2.05025 

3.3014 

1.94200 

2.9620 

2^ 

4 

2.17525 

3.7163 

2.06700 

3.3556 

2^ 

4 

2.30025 

4.1557 

2.19200 

3.7738 

2% 

4 

2.42525 

4.6196 

2.31100 

4.1946 

27/8 

3^ 

2.50386 

4.9239 

2.38015 

4.4494 

3^ 

2.62886 

5.4278 

2.50515 

4.9290 

BOILER  CONSTRUCTION. 


TAP  DRILLS. 

THIS  TABLE  SHOWS  THE  DIFFERENT  SIZES  OF  DRILL  THAT  SHOULD  BE  USED 
WHEN  FULL  THREAD  is  TO  BE  TAPPED. 

FOR  MACHINE  AND  HAND  TAP. 


Diameter  of  Tap 

No.  of 
Threads  to 
Inch 

Size  Drill 
for 
V  Thread 

Size  Drill 
for  U.  S. 
Standard 
Thread 

Size  Drill 
for 
Whitworth 
Thread 

!&•  - 

16   18  20 

5         5        11 

A 

A 

A  

16   18  20 

3        13      13 

ft 

16  18 

7        15 

U 

ii 

2 

16  18 

H  8  ' 

H" 

14  16  18 

M  &  %i 

A 

A 

w 

14  16  18 

u  n  n 

t" 

14   16 

21     11 

ii 

ii 

& 

14   16 

n  y» 

12   13   14 

y*  54.  u 

ia 

% 

?f 

12   13   14 

u  n  n 

A 

12   14 

7"       29 

^ 

-f& 

n 

12   14      . 

15        31 

YC, 

10  11   12 

y> 

U 

n   . 

10   11   12 

?/  i?  11 

%.  .          

10   11   12 

n  y-  y« 

5A 

5i 

B 

10   11   12 

y*  n  n 

5 

9   10    .  . 

45      23 

ii 

8? 

9  10 

i|  ^J 

i 

8 

«i 

g 

iH 

7       8 

15 

ii 

14 

1A 

7       8 

15             31 

in 

7 

i* 

ITS 

IX 

i* 

7 

if 

1% 

6 

1U 

Ifk 

1A 

1W 

6 

6 

1? 

l^f 

iili 

j'if 

6 

1^     1A 

1%.  . 

S       5U 

l^J     1^ 

l^g 

l*f 

IS- 

5       5K 

iH 

5 

•113 

1U 

1^ 

134 

5 

j3L 

iH  

4U  5 

1^     111 

15^ 

1M 

4U  5 

1A           14J 

2  

4U    . 

l«i 

1M 

1« 

OF  THE 

UNIVERSITY 


62 


THE  BOILER. 


PIPE  TAPS. 


Size  Pipe 

No.  of 
Threads   to 
the  Inch 

Diameter 
of  Drill 

Size  Pipe 

No.  of 
Threads   to 
the  Inch 

Diameter 
of  Drill 

U 

27 

ft 

3      

8 

3A 

M-  • 

18 

zy>.  . 

8 

313. 

R  
^  
%  

iii. 

18 
14 
14 
1W 
\\y> 

1 

!*:::::: 

6  
7  

8 
8 
8 
8 
8 

4^8 

.     5% 

^Te 

5*:  —  -.:: 

HH 

11^ 

2§ 

8  
9  

8 
8 

8  I/ 

vy> 

2K.-. 

8 

2U 

10.  . 

8 

10  U 

WEIGHTS  OF  ROUND  AND  SQUARE  STEEL.     PER  LINEAL  FOOT. 


Round, 

Square, 

Round, 

Square, 

Size, 
inches. 

Weight, 
Ibs. 

Weight, 
Ibs. 

Size, 
inches. 

Weight, 
Ibs. 

Weight, 
Ibs. 

P 

.094 

.120 

2ys 

12.06 

15.36 

.167 

.213 

2/4 

13.52 

17.22 

A 

.261 

.332 

2% 

15.07 

19.19 

N 

.375 

.478 

2}4 

16.70 

21.26 

T$ 

.511 

.651 

2% 

18.41 

23.44 

7& 

.668 

.851 

2% 

20.21 

25.73 

A 

.845 

1.076 

24.05 

30.62 

1.044 

1.329 

3M 

28.23 

35.94 

M 

1.503 

1.914 

31^ 

32.74 

41.68 

j^ 

2.046 

2.605 

3^€ 

37.57 

47.84 

i 

2.672 

3.402 

4 

42.77 

54.45 

iK 

3.382 

4.306 

4^> 

54.83 

69.81 

i-M 

4.175 

5.316 

5 

66.82 

85.08 

1% 

5.052 

6.432 

5L/ 

80.85 

102.94 

ijjj 

6.012 

7.655 

6 

96.22 

122.51 

15^ 

7.056 

8.984 

6^? 

112.92 

143.78 

1% 

8.183 

10.419 

7 

131.97 

166.75 

1  7^ 

9.394 

11.961 

7;M> 

150.34 

191.42 

2 

10.69 

13.61 

8 

171.04 

217.78 

BOILER  CONSTRUCTION.  63 

WEIGHTS  OF  FLAT  STEEL.     PER  LINEAL  FOOT. 


-C    t/3 

T3  J: 

THICKNESS,  INCHES. 

?J3 

A 

l/s 

& 

M 

A 

*A 

r7* 

1A 

5/S 

H 

% 

1 

1 

.21 

.43 

.638 

.850 

1.06 

1.28 

1.49 

1.70 

2.12 

2.55 

2.98 

1H 

.24 

.48 

.720 

.955 

1.20 

1.43 

1.68 

1.92 

2.39 

2.87 

3.35 

'3!88 

iM 

.27 

.53 

.797 

1.06 

1.33 

1.59 

1.86 

2.12 

2.65 

3.19 

3.72 

4.21 

iH 

.30 

.59 

.875 

1.17 

1.46 

1.76 

2.05 

2.34 

2.92 

3.51 

4.09 

4.68 

W 

.32 

.64 

.957 

1.28 

1.59 

1.92 

2.23 

2.55 

3.19 

3.83 

4.47 

5.10 

1^ 

.35 

.69 

1.04 

1.38 

1.73 

2.08 

2.42 

2.77 

3.46 

4.15 

4.84 

5.53 

1;14 

.38 

.75 

1.11 

1.49 

1.86 

2.23 

2.60 

2.98 

3.72 

4.47 

5.20 

5.95 

2 

.43 

.85 

1.28 

1.70 

2.12 

2.55 

2.98 

3.40 

4.25 

5.10 

5.95 

6.80 

2M 

.48 

.96 

1.44 

1.91 

2.39 

2.87 

3.35 

3.83 

4.78 

5.75 

6.69 

7.65 

2^ 

.53 

1.06 

1.59 

2.12 

2.65 

3.19 

3.72 

4.25 

5.31 

6.38 

7.44 

8.50 

2^ 

.59 

1.17 

1.75 

2.34 

2.92 

3.51 

4.09 

4.67 

5.84 

7.02 

8.18 

9.35 

3 

.64 

1.28 

1.91 

2.55 

3.19 

3.83 

4.46 

5.10 

6.38 

7.65 

8.93 

10.20 

3}4 

.69 

1.38 

2.07 

2.76 

3.45 

4.15 

4.83 

5.53 

6.91 

8.29 

9.67 

11.05 

3^ 

.75 

1.49 

2.23 

2.98 

3.72 

4.47 

5.20 

5.95 

7.44 

8.93 

10.41 

11.90 

3^ 

.80 

1.60 

2.39 

3.19 

3.99 

4.78 

5.58 

6.38 

7.97 

9.57 

11.16 

12.75 

4 

.85 

1.70 

2.55 

3.40 

4.25 

5.10 

5.95 

6.80 

8.50 

10.20 

11.90 

13.60 

4^ 

.96 

1.92 

2.87 

3.83 

4.78 

5.74 

6.70 

7.65 

9.57 

11.48 

13.39 

15.30 

5 

1.07 

2.13 

3.19 

4.25 

5.31 

6.38 

7.44 

8.50 

10.63 

12.75 

14.87 

17.00 

5^ 

1.17 

2.34 

3.51 

4.67 

5.84 

7.02 

8.18 

9.35 

11.69 

14.03 

16.36 

18.70 

6 

1.28 

2.55 

3.83 

5.10 

6.38 

7.65 

8.93 

10.20 

12.75 

15.30 

17.85 

20.40 

7 

1.49 

2.98 

4.46 

5.95 

7.44 

8.93 

10.41 

11.90 

14.87 

17.85 

20.83 

23.80 

8 

1.70 

3.40 

5.10 

6.80 

8.50 

10.20 

11.90 

13.60 

17.00 

20.40 

23.80 

27.20 

RULES   FOR  OBTAINING   APPROXIMATE   WEIGHT   OF 
WROUGHT  IRON. 

FOR    ROUND    BARS. 

RULE  :  Multiply  the  square  of  the  diameter  in  inches  by  the 
length  in  feet,  and  that  product  by  2.6.  The  product  will  be  the 
weight  in  pounds,  nearly. 

FOR    SQUARE    AND    FLAT    WROUGHT    BARS. 

RULE  :  Multiply  the  area  of  the  end  of  the  bar  in  inches  by 
the  length  in  feet,  and  that  3.32.  The  product  will  be  the  weight 
in  pounds,  nearly. 


WROUGHT    IRON,    ASSUMED    WEIGHT. 

A  cubic  foot   

A  square  foot,  1  inch  thick 

A  bar  1  inch  square,  1  foot  long 

A  bar  1  inch  square,  1  yard  long 


=  480       Ibs. 

40       Ibs. 

3  1-3  Ibs 

=    10       Ibs. 


64  THE  BOILER. 

RULE    FOR    FINDING    THE    SECTIONAL    AREA    OF    A    BAR    OF    WROUGHT 
IRON,  WHEN  WEIGHT  PER  FOOT  IS  GIVEN. 

Multiply  by  3  and  divide  by  10. 

RULE  FOR  FINDING  THE  WEIGHT  PER  FOOT.,  WHEN  AREA  IS  GIVEN. 

Divide  by  3  and  multiply  by   10. 


NOTES    ON    CONSTRUCTION. 

The  necessity  for  vigilance  and  supervision  of  boiler  designing 
and  construction  is  made  apparent  in  England  by  the  stringent 
laws  and  by  enforced  rules  and  practices  governing  the  same  in 
way  of  additional  factors  for  safety.  They  result  in  promoting 
good  work  and  care  in  the  operating  and  management  of  steam 
boilers. 

Additional  factors  for  safety  are  added  to  the  established  one 
of  5  due  to  deterioration  by  usage,  age  or  fuel. 

The  English  Board  of  Trade  has  established  and  tabulated  a 
table  of  percentage  of  increase  of  factor  of  safety  and  cites  reasons 
for  such  additional  proportions. 

All  boilers  must  be  designed  and  constructed  according  to  their 
specifications,  viz. :  Holes  to  be  drilled  when  shell  plates  have 
been  rolled ;  straps  or  cover  plates  not  less  than  jj^j  of  plates  they 
cover;  in  butt  joints  rivet  sections  must  be  75  per  cent  over 
rivets  in  single  shear  and  circumferential  seams  at  least  one-half 
the  percentage  of  longitudnal  seam. 

The  increased  factor  of  safety  is  insisted  on  when  conditions 
are  as  follows : 

TABLE. 

PERCENTAGE 

OF 
INCREASE 

A.  =      .1       To  be  added  when  all  holes  are  fair  and  good  in  the  long  seam, 

but  drilled  out  of  place  after  bending. 

B.  =      .2       When  all  holes  are  fair  and  good  in  longitudinal  seams,  but 

drilled  before  bending. 


. 

BOILER  CONSTRUCTION.  65 

PERCENTAGE 

OF 

INCREASE 

C.  =      .2       When  all  holes  are  fair  and  good  in  longitudinal  seams,  but 

punched  after  bending. 

D.  =      .3        When  all  holes  are  lair  and  good  in  longitudinal  seam  but 

punched  before  bending. 

E.  =      .7       When  all  holes  are  not  fair  and  good  in  longitudinal  seam  (and 

increased  according  to  values). 

F.  =      .8       When  holes  are  all  fair  and  good  in  the  circumferential  seams, 

but  drilled  out  of  place  after  bending. 

G.  =      .1       When  all  holes  are  fair  and  good  in  the  circumferential  seams, 

but  drilled  before  bending. 
H.     =      .1       When  holes  are  fair  and  good  in  the  circumferential  seams,  but 

punched  after  bending. 
I.       =      .15     If  the  holes  are  all  fair  and  good  in  the  circumferential  seams, 

but  punched  before  bending. 
J.      =      .15     If  the  holes  are  not  fair  and  good  in  the  circumferential  seams 

(and  increased  according  to  values). 
K  .2       If  the  double  butt  straps  are  not  fitted  to  the  longitudinal 

seams  and  said  seams  are  lap  and  double  riveted. 
L.  .  07     If  double  butt  straps  are  not  fitted  to  the  longitudinal  seams 

and  said  seams  are  lap  and  triple  riveted. 
M.     =      .3       If  only  single  butt  straps  are  fitted  to  the  longitudinal  seams 

and  said  seams  are  double  riveted. 
N.     =      .15     If  only  single  butt  straps  are  fitted  to  the  longitudinal  seams 

and  said  seams  are  triple  riveted. 
O.      =      .1       When  any   description  of  joint  in   the   longitudinal  seam  is 

single  riveted. 
P.      =      .  2       If  all  holes   are   punched  small  and   reamed   afterwards    or 

drilled  out  in  place. 
Q.     =      .4       If  the  longitudinal  seams  are  fitted  with  single  butt  straps 

and  are  single  riveted. 
R.     =      .4       When   material  or  workmanship   is    according   to   inspector 

doubtful  or  not  the  best  (then  the  factor  is  increased  accord- 
ingly). 

S.  =  .  1  If  the  circumferential  seams  are  lap  joints  and  double  riveted. 
T.  =  .2  If  the  circumferential  seams  are  lap  joints  and  single  riveted. 
U.  =  .25  When  the  circumferential  seams  are  lap  and  the  plates  are 

not  entirely  under  or  over  covers,  and  1.65  to  be  added  if  the 

boiler  is  not  open  to  inspection  during  the  whole  period  of 

its  construction. 

The  benefits  derived  from  these  additional  factors  of  safety  will 
be  the  means  of  bringing  the  science  of  boiler  designing  and  work 
of  construction  up  to  a  high  standard. 

In  designing  seams  reason  must  govern  when  calculations  are 
made,  for  if  too  great  a  pitch  is  used  the  plate  cannot  be  drawn 
together  without  springing  of  plate  or  heads  of  rivets  coming  off, 
and  so  prevent  making  a  tight  caulking  edge. 


66  THE  BOILER. 

Each  joint  will  be  taken  np  separately  as  the  strength  of  a  joint 
is  less  than  that  of  the  solid  plate  due  to  cutting  away  for  rivet  holes 
and  the  single  riveted  lap  joint  is  the  weakest  designed. 

Tests  have  been  made  on  various  designed  joints,  and  as  it 
would  be  impossible  to  test  all  joints  constructed,  calculations  from 
practice,  factors  and  co-efficients  must  be  relied  on  and  followed  up ; 
these  have  proved  satisfactory  when  construction  has  been  care- 
fully complied  with  according  to  designs. 

The  aim  in  boiler  construction  is  to  have  the  percentage  of 
strength  in  rivet  and  plate  as  near  equal  as  possible. 

The  maximum  strength  of  a  boiler  is  calculated  from  its  weakest 
point,  and  the  subject  of  seams  in  various  forms  and  design  will  be 
taken  up  later ;  also  boiler  diameter,  material  thickness  of  same ; 
rivets,  their  diameter;  shearing  strength,  if  single  or  double;  pitch 
of  rivets,  number  of  rivets  in  joints;  butt  straps  and  factors,  such 
as  constants,  taken  into  consideration  when  calculating  the  strength 
of  a  seam  and  varying  according  to  conditions ;  methods  of  construc- 
tion and  design  of  joint  or  difference  in  material. 

The  necessity  for  care  in  designing  and  constructing  to  resist 
great  forces  is  clearly  shown  by  the  following  calculation :  A  com- 
mon size  boiler  60"  X  16'  has  approximately  32,145  square  inches 
of  bursting  area  and  at  a  pressure  of  100  pounds  it  has  a  total  of 
1,607  tons  of  energy  or  bursting  pressure;  with  the  higher  pressures 
now  used,  this  hazard  increases. 

The  English  Board  of  Trade,  a  recognized  authority  on  steam 
boilers,  says  that  the  rivet  percentage  of  seam  should  be  in  excess 
of  the  plate  and  when  computing  the  rivet  section  when  steel  plates 
and  rivets  are  used  the  rivet  section  must  be  divided  by  28/23.  If 
iron  rivets  are  used  with  steel  plates  then  the  rivet  section  must  be 
y%  times  greater  than  plate  section  and  be  divided  by  13/8. 

When  describing  strains,  the  action  of  shearing  rivets  means  to 
shear  across  its  diameter.  The  tearing  strain  refers  to  the  action 
of  tearing  apart  of  plate.  The  crushing  strain  is  the  action  to 
crush  or  rupture  the  plate  between  rivet  holes  and  edge  of  plate. 

In  calculations  for  rivet  strength  the  diameter  of  the  rivet  hole 
will  be  taken  and  not  the  diameter  of  the  rivet,  for  the  rivet  must 
fill  the  rivet  hole. 


BOILER  CONSTRUCTION.  67 

The  reader  will  observe  in  following  calculations  that  decimals 
will  be  omitted  when  of  minor  value. 

LEGEND. 
SYMBOLS  USED  IN  FORMULAS 

P=  pressure 

p=  pitch  of  rivets 
Pm  =  maximum  pitch 

N  =  number  of  rivets 
Pd  =  diagonal  pitch  of  rivets 

D  =  diameter  of  boiler 

d  =  diameter  of  rivet  hole 

T  =  Thickness  of  plate 
%  =  percentage 

V=  distance  between  rows 

E  =  distance  center  of  rivets  to  edge  of  plate  (lap) 
TS  =  tensile  strength  of  plate 
AR  =area  of  rivet  hole 

F  =  factor  of  safety 

A  coefficient  is  a  prescribed  amount  to  make  up  for  any  defects 
reducing"  strength  of  plate  due  to  punching,  riveting,  caulking,  &c. 

A  factor  of  safety  is  the  difference  between  the  safe  working  and 
bursting  pressures. 

It  is  well  to  explain  here  that  calculations  of  joints  are  based  on 
the  principle  that  sections  of  the  same  do  not  vary,  except  according 
to  the  joints  designed;  the  boiler,  figuratively  speaking,  is  composed 
of  rings,  each  one  having  the  same  amount  of  plate  width  and  pitch 
of  rivets  and  the  weakest  part  of  this  supposed  ring  is  the  base  of 
the  maximum  strength.  In  the  process  of  computing  calculations 
this  will  appear  clear  to  the  student. 

The  rules  for  calculating  strength  of  joints  vary  in  formulas 
and  results,  but  as  stated  in  previous  pages  the  rules  the  writer  has 
used  in  connection  with  designing,  testing  and  inspecting  have  been 
based  on  experiments  and  found  in  practice  to  have  a  factor  of  safety 
of  reasonable  margin. 

While  in  computing  joints  the  aim  is  to  get  the  plate  and  rivet 
strength  as  near  equal ;  favoring  the  rivet ;  it  must  be  remembered 
that  a  variance  in  pitch  will  vary  efficiencies  as  will  also  the  diameter 
of  a  rivet,  these  being  of  standard  sizes  and  varying  in  sixteenths ; 
some  of  the  rules  will  show  an  excess  of  rivet  strength  or  even 
plate,  and  will  appeal  to  the  reader  that  a  smaller  diameter  of  rivet 
or  greater  pitch,  or  a  lower  or  higher  tensile  strength,  would  affect 
the  factors  in  securing  the  best  possible  efficiencies. 


68 


THE  BOILER. 


In  the  following  rules  in  connection  with  boiler  as  outlined  there 
are  calculations  to  make  from  material  and  ratios  for  efficiencies. 
The  strength  of  rivets  has  been  computed  from  exhaustive  tests  and 
as  the  subject  of  rivet  shearing  will  be  a  factor  in  calculating  seams 
of  efficiency  it  may  be  well  to  make  some  explanations.  The  neces- 
sary force  to  shear  a  rivet  in  single  shear  is  38,000  Ibs.  to  square 
inch  of  cross  section  of  rivet.  The  strain  necessary  to  shear  a  rivet 
in  double  shear  is  85  per  cent  more  than  in  single  shear. 

EXAMPLE: 

Rule  to  find  strength  of  rivet  in  single  shear:  Multiply  area  of  rivet 
hole  by  shearing  resistance  of  rivet. 

FORMULA: 

A  X  S  =  strength  of  rivet  in  single  shear 
EXAMPLE: 

.5185  =area  of  rivet  hole 

3  8000=  shearing  resistance 


41480000 
15555 


SHEAR 


19,703  =strength  of  one  rivet  in  single  shear 


38000  =lbs.  single  shear 

.  85  =  %  more  for  double 
shear 


190000 
304000 

32300.00  Ibs.  =85%  of  38000 
Ibs. 


DOUBLE  SHEAR 


adding  the  value  to  the  above 


3  8000=  single  shearing  strength 
32300  =  85%  added 


70300  =  shearing  strength  of  a  rivet  in  double  shear 


CHAPTER  IV. 

BRACES  AND  REINFORCING. 

While  there  are  boilers  being  made  today  that  have  strength 
in  designed  circular  forms,  the  many  in  use  and  those  being  con- 
structed have  surfaces  requiring  reinforcements,  some  having  an 
excess  over  other  types  and  the  high  pressures  now  in  demand  re- 
quire the  best  methods  and  improved  design  of  brace. 

This  is  a  subject  of  as  much  importance  as  the  designing  of  a 
joint  and  requires  careful  selection,  proportioning  and  attaching 
braces  to  counteract  strains  that  may  be  due  to  resisting  bursting 
pressures,  and  those  of  contraction,  expansion  and  collapsing. 

Various  designed  braces  and  stays  have  been  in  use  and  are  as 
varied  in  stability,  some  having  minimum  amount  of  strength,  due 
to  their  structural  weakness;  again  while  some  have  the  desired 
form  and  strength,  location  or  principle  of  attaching  same  has  de- 
preciated their  value  as  a  reinforcement. 

The  subject  of  bracing  is  broad  and  could  be  treated  inexhaust- 
ively,  this  owing  to  the  many  necessities  and  forms  where  each 
must  necessarily  be  worked  out  separately.  It  is  the  intention 
to  take  up  the  most  general  methods,  such  as  stay  bolts,  formed 
braces,  stay  tubes,  crown  bars,  and  angle  irons. 

Factors  that  are  taken  into  consideration  are 
Structural, 
Design, 

Tensile  strength, 
Location,  and 
Principle  of  attaching. 

In  using  rivets  for  braces  it  is  customary  to  have  the  combined 
area  equal  to  \l/\.  times  the  brace  area. 

STAY    BOLTS. 

The  use  of  stay  bolts  or  stud  stays  for  bracing  is  not  at  best  a 
very  satisfactory  method  of  reinforcement,  this  owing  to  position 

69 


70  THE  BOILER. 

and  conditions,  especially  in  fire  box  boilers  where  strains  are  caused 
by  a  bending  force  through  the  expansion  of  fire  sheet,  a  pulling 
strain  by  the  collapsing  and  bursting  pressures  and  by  that  of 
vibration. 

Care  is  necessary  in  selecting  the  best  material ;  the  U.  S.  Govern- 
men  requires  the  same  tests  to  be  made  in  accordance  with  those  of 
plate  used  in  connection  with  boilers  coming  under  the  supervision 
of  the  Federal  Government.  In  physical  and  chemical  tests  results 
must  show  according  to  prescribed  rules.  Constant  vibration  is  a 
menace  to  safety  and  braces  are  subject  to  and  effected  more  by  it 
than  the  strains  from  the  pressures  and  more  than  the  shell  tubes 
or  rivets  are  by  it. 

The  best  material  for  this  strain  is  that  made  from  piling  material 
over  that  which  is  made  from  the  bloom,  this  being  due  to  its 
lamina  structure. 

Requirements  to  look  for  in  brace  materials  are : 

Tensile  strength, 

Elongation, 

Reduction  of  area, 

Elasticity. 

Vigilance,  careful  and  frequent  tests  and  inspections  of  the  stay 
bolts  are  necessary,  for  the  force  of  expansion,  contraction,  tension, 
bending  and  vibration  are  severe.  In  the  work  of  inserting  and 
finishing  this  part  of  boiler  construction  defects  often  develop,  this 
by  stripping  of  threads  when  entering  inner  plate,  again  by  hammer- 
ing over  ends ;  when  this  does  occur  the  value  of  the  brace  is  gone. 
The  design  of  the  brace  (stay  bolt)  is  weak  in  the  first  place 
for  the  threads  act  in  a  measure  as  an  initial  fracture,  especially  so 
when  one  portion  of  thread  is  cut  a  little  deeper  than  the  balance. 
The  hollow  type  of  stay  bolt  has  commendable  features,  viz. :  The 
available  admission  of  air  to  the  (rich  in  heat  units)  volatile  gases 
from  fuel  in  furnace  (these  gases  having  a  heat  value  of  62,000  heat 
units  per  pound,  while  the  carbon  or  coke  has  only  14,500),  the 
heating  of  the  air  before  coming  in  contact  and  mixing  with  same, 
thus  producing  economical  results,  from  minimum  "heat  absorbed  by 
air  from  water ;  another  feature  that  commends  itself  is  instant 
notice  of  any  failure. 


BRACES  AND  REINFORCING.  71 

Rule  to  find  safe  working  pressure  on  flat  surfaces  when  thick- 
ness of  plate  and  pitch  of  stay  bolts  are  known : 

Multiply  the  constant  given  for  the  specified  thickness  by  the 
thickness  of  plate  squared  in  sixteenths  and  divide  by  the  greatest 
pitch  squared. 


FORMULA: 
C  X  T2 


'Safe  working  pressure 


What  is  the  safe  working  pressure  on  a  curved  surface  less  than 
a  true  circle  ?     Plate  7/16  thick  and  stay  bolts  5"  X  6"  centers. 

EXAMPLE: 
7  =  &=  thickness 
7  112  =••  constant  as  provided  for 

49  =  thickness  squared 
49  =  thickness  squared 

pitch  =    6"   1008 
6     448 


pitch  squared  =36    )S488  (152  Ibs.  safe  working  pressure 
36 

188 
180 


88 
72 

16 


Note  constants  for  specific  conditions  as  used  in  following  ex- 
amples : 

For  a  plate  three-fourths  of  an  inch  thick,  stayed  9-inch  by 
10-inch  centers : 

120X144 

Working  pressure  = —  —  =  172  pounds. 

100 

For  a  plate  nine-sixteenths  of  an  inch  thick,  screw  stays  with 
nuts,  stays  pitched  9-inch  by  10-inch  centers: 

135X81 

Working  pressure  = —        —  =  109  pounds. 
100 


72  THE  BOILER. 

For  a  plate  three-fourths  of  an  inch  thick,  supported  by  stays 
with  double  nuts,  without  washers  or  doubling  plates,  10-inch  by 
12-inch  centers: 

170X144 

Working  pressure  = —  —  =  170  pounds. 

144 

For  plate  one-half  inch  thick,  with  washers  three-eighths  of  an 
inch  thick,  stayed  10-inch  by  12-inch  centers: 

160X101.60 

Working  pressure  = —  —  =  112  pounds 

144 

For  plate  five-eighths  of  an  inch  thick,  with  doubling  plate  seven- 
sixteenths  of  an  inch  thick,  stayed  by  14-inch  by  14-inch  centers : 

200X149.81 

Working  pressure  = —  —  =  152  pounds. 

196 

For  plate  five-eighths  of  an  inch  thick,  with  tees  or  angle  bars 
one-half  of  an  inch  thick,  stayed  by  14-inch  by  14-inch  centers : 

200X167.96 

Working  pressure  = —  —  =  171  pounds. 

196 

Plates  heated  for  working  must  be  annealed  afterwards. 
The  diameter  of  a  screw  stay  shall  be  taken  at  the  bottom  of 
the  thread,  provided  it  is  the  least  diameter  of  the  stay. 

Flat  heads  not  exceeding  20  inches  in  diameter  may  be  used 
unsupported  at  pressure  allowed  by  following  rule : 

Multiplying  constant  by  thickness  of  head  in  sixteenths  squared, 
and  dividing  by  half  of  area  to  be  supported,  gives  the  pressure 
allowed. 


FORMULA: 
CXT2 


=  P 


y2ot  A 

Where  P=steam  pressure  allowable  in  pounds. 
T  =  thickness  of  material  =  %  =}f . 
A  =area  of  head  in  inches  =314". 
C  =  112  for  plates  -^  of  an  inch  and  under. 
C  =120  for  plates  over  ^  of  an  inch. 
Provided,  The  flanges  are  made  to  an  inside  radius  of  at  least  1^  inches. 


BRACES  AND  REINFORCING.  73 

EXAMPLE: 

Required  the  working  pressure  of  a  flat  head  20  inches  in  diameter  and 

of  an  inch  thick. 

120  =  constant  as  provided  for 
144=head  in  sixteenths  squared 

480 
480 
120 

one-half  area  of  head  =  157)  17280  (110  pounds  safe  working  pressure 

158 
157 


10 
FLAT    SURFACES. 

The  maximum  stress  allowable  on  flat  plates  supported  by  stays 
shall  be  determined  by  the  following  rule : 

All  stayed  surfaces  formed  to  a  curve  the  radius  of  which  is 
over  21  inches,  excepting  surfaces  otherwise  provided  for,  shall  be 
deemed  flat  surfaces. 

CONSTANTS. 

C  =  112  for  screw  stays  with  riveted  heads,  plates  seven-sixteenths  of  an  inch 
thick  and  under. 

C  =  120  for  screw  stays  with  riveted  heads,  plates  above  seven-sixteenths 

of  an  inch  thick. 
C  =  120  for  screw  stays  with  nuts,  plates  seven-sixteenths  of  an  inch  thick 

and  under. 

C=125  for  screw  stays  with  nuts,  plates  above  seven-sixteenths  of  an  inch 

thick  and  under  nine-sixteenths  of  an  inch. 
C  =135  for  screw  stays  with  nuts,  plates  nine-sixteenths  of  an  inch  thick  and 

above. 

C  =  170  for  stays  with  double  nuts  having  one  nut  on  the  inside  and  one 
nut  on  the  outside  of  plate,  without  washers  or  doubling  plates. 

C  =160- for  stays  fitted  with  washers  or  doubling  strips  which  have  a  thick- 
ness of  at  least  .5  of  the  thickness  of  the  plate  and  a  diameter  of  at 
least  .5  of  the  greatest  pitch  of  the  stay,  riveted  to  the  outside  of 
the  plates,  and  stays  having  one  nut  inside  of  the  plate,  and  one  nut 
outside  of  the  washer  or  doubling  strip.  For  T  take  72  per  cent  of 
the  combined  thickness  of  the  plate  and  washer  or  plate  or  doubling 
strip. 

C  =200  for  stays  fitted  with  doubling  strips  which  have  a  thickness  equal  to 
at  least  .5  of  the  thickness  of  the  plate  reinforced,  and  covering  the 
full  area  braced  (up  to  the  curvature  of  the  flange,  if  any),  riveted 
to  either  the  inside  or  outside  of  the  plate,  and  stays  having  one  nut 
outside  and  one  inside  of  the  plates.  Washers  or  doubling  plates  to 
be  substantially  riveted.  For  T  take  72  per  cent  of  the  combined 
thickness  of  the  two  plates. 


74  THE  BOILER. 

C=200  for  stays  with  plates  stiffened  with  tees  or  angle-bars  having  a 
thickness  of  at  least  two-thirds  the  thickness  of  plate  and  depth  of 
webs  at  least  one-fourth  of  the  greatest  pitch  of  the  stays,  and  sub- 
stantially riveted  on  the  inside  of  the  plates,  and  stays  having  one 
nut  inside  bearing  on  washers  fitted  to  the  edges  of  the  webs,  that 
are  at  right  angles  to  the  plate.  For  T  take  72  per  cent  of  the 
combined  thickness  of  web  and  plate. 

No  flat  plates  or  surfaces  shall  be  unsupported  at  a  greater 
distance  than  18  inches. 

Multiply  the  constant  120  by  the  thickness  squared  in  six- 
teenths and  divide  product  by  the  pitch  of  stay  squared : 

FORMULA: 

CXT2 

—  =  working  pressure 
P2 

LEGEND: 

T  =  thickness  of  plate  =  ^  =  7 
P=pitch  =  10" 
C=  constant  =  120 

EXAMPLE: 

120=  constant 
49=plate  squared  in  16ths 

1080 
480 


pitch  squared  =  100)5880  (58.  8  Ibs.  pressure  allowed  or  59  Ibs.  nearly 
500 


880 
800 

80 

Rules  adopted  by  authorities  that  have  proven  satisfactory  from 
tests  and  usage  and  adopted  by  the  U.  S.  Government  and  reputable 
boiler  manufacturers  are  given  in  this  chapter,  and  in  connection 
material  and  workmanship  is  considered  to  be  the  best,  fitted  accur- 
ately and  properly  secured. 

Exhaustive  tests  have  been  made  by  the  highest  authorities, 
governments,  scientific  and  mechanical  and  results  have  shown  that 
there  are  some  differences;  sufficient  reasons  in  the  fact  show  that 
the  majority  are  near  enough  to  establish  formulas  that  have  liberal 
margins  of  safety. 

Judgment  must  be  governed  by  conditions  and  construction 
when  out  of  the  ordinary  and  special  consideration  given,  always 


BRACES  AND  REINFORCING.  75 

allowing"  a  reasonable  factor  of  safety  for  an  unusual  form  or 
position. 

For  all  stays  the  least  sectional  area  shall  be  taken  in  calculating 
the  stress  allowable. 

All  screw  stay  bolts  shall  be  drilled  at  the  ends  with  a  one- 
eighth  inch  hole  to  at  least  a  depth  of  one-half  inch  beyond  the 
inside  surface  of  the  sheet.  Stays  through  laps  or  butt  straps  may 
be  drilled  with  larger  hole  to  a  depth  so  that  the  inner  end  of  said 
larger  hole  shall  not  be  nearer  than  the  thickness  of  the  boiler  plates 
from  the  inner  surface  of  the  boiler. 

Such  screw  stay  bolts,  with  or  without  sockets,  may  be  used  in 
the  construction  of  marine  boilers  where  fresh  water  is  used  for 
generating  steam:  Provided,  hoiucver,  that  screw  stay  bolts  of  a 
greater  length  than  24  inches  will  not  be  allowed  in  any  instance, 
unless  the  ends  of  said  bolts  are  fitted  with  nuts.  Water  used  from 
a  surface  condenser  shall  be  deemed  fresh  water. 

Holes  for  screwed  stays  must  be  tapped  fair  and  true  and  full 
thread. 

The  ends  of  stays  which  are  upset  to  include  the  depth  of  thread 
shall  be  thoroughly  annealed  after  being  upset. 

The  sectional  area  of  pins  to  resist  double  shear  and  bending, 
accurately  fitted  and  secured  in  crow  feet,  sling,  and  similar  stays, 
shall  be  at  least  equal  to  required  sectional  area  of  the  brace. 
Breadth  across  each  side  and  depth  to  crown  of  eye  shall  be  not 
less  than  .35  to  .55  of  diameter  of  pin.  In  order  to  compensate  for 
inaccurate  distribution  the  forks  should  be  proportioned  to  support 
two-thirds  of  the  load,  thickness  of  forks  to  be  not  less  than  .66  to  .75 
of  the  diameter  of  pins. 

The  combined  sectional  area  of  rivets  used  in  securing  tee  irons 
and  crow  feet  to  shell,  said  rivets  being  in  tension,  shall  be  not  less 
than  the  required  sectional  area  of  brace.  To  insure  a  well-pro- 
portioned rivet  point,  the  total  length  of  shank  shall  closely  approx- 
imate the  grip  plus  1.5  times  the  diameter  of  the  shank.  All  rivet 
holes  shall  be  drilled.  Distance  from  center  of  rivet  hole  to  edge 
of  tee  irons,  crow  feet,  and  similar  fastenings  shall  be  so  propor- 
tioned that  the  net  sectional  areas  through  sides  at  rivet  holes  shall 
equal  the  required  rivet  section.  Rivet  holes  shall  be  slightly  coun- 
tersunk in  order  to  form  a  fillet  at  point  and  head. 


76  THE  BOILER. 

CONSTANTS  PROVIDED  FOR  THE  VARYING  REQUIREMENTS. 

C=9,000  for  tested  steel  stays  exceeding  2^  inches  in  diameter. 

C  =  8,000  for  tested  steel  stays  1^£  inches  and  not  exceeding  2^  inches  in 
diameter,  when  such  stays  are  not  forged  or  welded.  The  ends,  how- 
ever, may  be  upset  to  a  sufficient  diameter  to  allow  for  the  depth  of 
the  thread.  The  diameter  shall  be  taken  at  the  bottom  of  the  thread, 
provided  it  is  the  least  diameter  of  the  stay.  All  such  stays  after 
being  upset  shall  be  thoroughly  annealed. 

C=8,000  for  a  tested  Huston  or  similar  type  of  brace,  the  cross-sectional 
area  of  which  exceeds  5  square  inches. 

C=7,000  for  such  tested  braces  when  the  cross-sectional  area  is  not  less 
than  1.227  and  not  more  than  5  square  inches,  provided  such  braces 
are  prepared  at  one  heat  from  a  solid  piece  of  plate  without  welds. 

C  =6,000  for  all  stays  not  otherwise  provided  for. 


Rule  to  find  sectional  area  of  a  brace  to  support  a  given  area 
when  pressure  is  known :  Multiply  area  to  be  supported  by  pressure 
per  square  inch  and  divide  by  constant  as  provided  for  size  and  ma- 
terial of  brace. 

FORMULA: 

AxP 

—  =  sectional  area  of  brace 
LEGEND:  C 

A  =area  to  be  supported  =36  square  inches 

P  =  pressure  =  150  Ibs. 

C  =  co nstant=  brace  steel  having  1^  diameter  =  8000 

EXAMPLE: 

36"  =  sectional  area  to  be  supported 
150  =  Ibs.  pressure 

1800 
36 


constant  for  1M  steel  brace  =  8000)  54000000  (.6750  =43/64  or  ^   cross-sec- 

48000  tional  area  nearly 

60000 
56000 

40000 
40000 


BRACES  AND  REINFORCING.  77 

Rule  to  find  strain  on  a  stay  bolt :    Multiply  the  area  supported  by 
the  stay,  by  the  pressure. 

FORMULA: 

A  X  P  =  strain  on  stay 
LEGEND: 

A    =area  =6"  X6"  =  36  square  inches 

P     ^pressure  =  150  Ibs.  EXAMPLE: 

36  square  inches  =area 
150=lbs.  pressure 


1800 
36 

5400  =lbs.  strain  on  bolt 

Rule  to  find  greatest  area  one  stay  bolt  may  support :     Multiply 
area  of  stay  bolt  by  constant  and  divide  by  working  pressure. 

FORMULA: 
AXC 

—  = limit  of  area  to  be  supported  by  one  bolt 
P 
LEGEND: 

C  =constant  =6000  Ibs.  allowed  per  cross-sectional  area 
A  =area  of  stay  bolt  =  j|  =  .  69029 
P  =  pressure  =  150  Ibs. 

EXAMPLE: 

. 69029  =area  of  ft  bolt 
6000=  constant 


pressure  =  150) 41417. £000(27. 6"  =limit  of  area  to  be  sup 
300  ported  by  one  bolt 

1141 
1050 


917 
900 

17 

Rule  to  find  number  of  stay  bolts  to  support  a  given  area  when 
pressure  is  given : 

Multiply  area  to  be  supported  by  pressure  and  divide  sum  by 
constants  as  provided  for.  Constants  for  the  different  size  bolts  to 
be  used  are  as  follows: 

for    %"  diameter  use  constant  4000, 
"   W  6000, 

if  for  over  that  diameter  and  up  to  2^"  8000, 

being  pounds  pressure  per  square  inch  of  cross-sectional  area. 


THE  BOILER. 

FORMULA : 

AXP 

—  =  number  of  stay  bolts 


The  following  example  is  where  bolts  are  %"  in  diameter 

LEGEND: 

A  =area  to  be  supported  =800  square  inches 
P  =  pressure  =  100  Ibs. 
C  =  constant  =4000 

EXAMPLE  : 

800  =area  to  be  supported 
100=lbs.  pressure 

constant  =4000) 80000  (20  stay  bolts  required 
8000 


0 

The  following  example  is  where  bolts  are  1^6"  diameter 

LEGEND: 

A  =area  to  be  supported  =  500 
P  =pressure  =  120  Ibs. 
C  =  constant  =6000 

EXAMPLE: 

500  =area  to  be  supported 
120=lbs.  pressure 


10000 
500 

constant  =6000)60000(10  stay  bolts  required 
6000 


Rule  to  find  centers  for  stay  bolts  when  pressure,  area  to  be 
supported  and  constant  provided  for  stay  bolt  are  known :  Multiply 
area. of  stay  bolt  by  constant  and  divide  by  pressure. 

FORMULA: 

AXC 

—  =  centers  of  stay  bolts 
P 
LEGEND: 

A  =area  to  be  supported  =  .  3750 
C  =  constant  =  4000 
P  =  pressure  =  150  Ibs. 


BRACES  AND  REINFORCING.  79 


EXAMPLE : 

.3750  =area  of  stay  bolt 
4000  =  constant 


pressure  =  1 50)1 500. 0000  ( 10"=  centers  of  stay  bolts 
150 


Rule  to  find  area  of  stay  bolt.  Multiply  centers  of  stay  bolt  by 
pressure  and  divide  by  constant  4,000;  the  quotient  is  area  of  stay 
bolt  required. 


FORMULA: 

CBXP 

—  =area  of  stay  bolt 


LEGEND: 


P  =pressure  =  150  Ibs. 
C  =  constant  =  4000 . 
CB  =  center  of  stay  bolt  =10" 

EXAMPLE: 


10"  =  center  of  stay  bolt 
150  =  pressure 


500 
10 

constant  =4000)  1500.  0000  (.  3750  =area  of  stay  bolt 
1200  0 


300  00 
280  00 


20  000 
20  000 


English  Board  of  Trade  rule  to  find  safe  working  pressure  when 
steel  stay  bolts  are  used  and  are  screwed  into  plates  and  fitted  with 
nuts : 

Multiply  constant  80  (plus  25%  for  steel)  by  thickness  of  plate 
in  sixteenths  plus  one  sixteenth  squared;  divide  by  pitch  of  rivet 
squared  minus  6;  product  is  safe  working  pressure. 

FORMULA: 
-  =safe  working  pressure 


P2— 6 


80  THE  BOILER. 


LEGEND: 

T  =  thickness  of  plate  = 

P  =  pitch  =  7 

C  =  constant  =80 

%  =25%  added  for  steel 


EXAMPLE: 


80  =  constant 

20  =25%  added  for  steel 

pitch  =  7       100 

7          64  =  ^  +  ^  or  T86,  squared 


pitch  squared  =  49       400 
minus  6     600 


43   )  6400  (148  =lbs.  pressure  for  steel  bolts 
43 

210  7=  ;&=  thickness  of  plate 

172  1  =  A  added 


380  8=A 

344  8 

36  64  =T8e  squared 

Rule  to  find  pitch  of  stay  bolts  : 

Multiply  constant  112  by  the  square  of  the  thickness  of  plate  in 
sixteenths  of  an  inch;  divide  this  product  by  steam  pressure  and 
extract  the  square  root  of  quotient. 

FORMULA  : 


CXT2 
\/—       —  =  pitch  of  stay 


LEGEND: 


C=  constant  =  112 

T  =  thickness  of  plate  =  & 

P=  pressure  =  150 

EXAMPLE: 

112  =  constant 
49=  the  square  of 


1008 
448 


150)5488(36 

450  square  root  of  36  is  6"  pitch 


988 

900  6)36(6"  =  square  root  =  pitch  of  bolts 

36 
88  — 


BRACES  AND  REINFORCING.  81 

TABLE  OF  STAY  BOLTS,  PLATE,  PITCH  AND  PRESSURE. 


Pressure 
in 
pounds. 

Centers  of  Stay  Bolts. 

%"  Plate 

tV'  Plate. 

Y*'  Plate. 

20 
40 
60 
80 
100 
120 
140 
150 
160 

llM"pi 
8 
6^ 
5^ 
5 
4^ 
4M 
4^ 
4 

tch 

13"       pi 
9M 

7^ 

$ 

$ 

4<4 
4^ 

tch 

15"       pi 

WsH 

$ 

f>Ys 
$5A 
5^ 
5^ 

tch 

Diam.  of 
stay  bolt 

H" 

1" 

IK" 

CROW    FOOT    OR    FORMED    BRACES. 

As  stated  in  preceding  pages  the  many  and  varied  surfaces  to 
be  braced  requiring  specific  methods  and  application  of  bracing,  the 
H.  T.  boiler,  having  the  minimum  amount  of  flat  surface  and  condi- 
tions favorable  to  apply  the  selection  for  suitable  type  of  brace,  is 
confined  to  the  one  with  minimum  structural  weakness,  taking  the 
Huston,  McGregor,  or  of  equal  stability. 

In  calculating  the  necessary  reinforcement  by  bracing — the  area 
of  surface  to  be  stayed,  and  working  pressure  is  considered ;  while 
the  thickness  of  head  is  a  factor  in  its  strength,  the  necessity  for 
braces  in  lieu  of  increasing  the  thickness  of  head  to  self  supporting, 
is  without  comment. 

In  all  types  of  stays  the  least  sectional  area  must  be  taken  in 
calculating  the  stress  allowable  and  the  combined  sectional  area  of 
rivets  used  in  securing  crow  feet,  angle  irons  and  such  form  of 
braces,  necessitating  rivets,  must  not  be  less  than  the  required  sec- 
tional area  of  brace;  all  rivet  holes  to  be  drilled,  and  the  distance 
from  center  of  hole  to  edge  of  palm  or  brace  surface  shall  be  so 
proportionate  that  the  net  sectional  areas  through  sides  at  rivet  holes 
shall  equal  the  rivet  section;  rivet  holes  in  plate  to  be  slightly 
countersunk. 

Taking  a  flat  surface  in  head  above  water  line,  say  800  square 
inches,  to  proportionate  a  proper  thickness  of  head  for  that  unstated 


82  THE  BOILER. 

portion  it  would  be  necessary  to  have  the  thickness  of  head  by  rule 
as  follows : 

Multiply  area  by  pressure  and  again  by  constant ;  divide  product 
by  tensile  strength  multiplied  by  10;  the  quotient  will  be  the  thick- 
ness for  unstayed  portion. 

LEGEND:  FORMULA: 

A  =  area—  800  square  inches  AxPxC 

P  =  pressure  =  100  —  =  thickness    for  un- 

C  =  constant  =7000  Ibs.  per  square  inch         TS  X  10  stayed  portion 

TS  =  tensile  strength  =60000 

EXAMPLE: 

800=  area 

100  =  pressure 

tensile  strength  =60000       80000 
multiplied  by  10  7000  =  constant 

600000)560000000(933  =ftf  inch  nearly  in  thickness 
5400000 


2000000 
1800000 

2000000 
1800000 


200000 

This  would  not  be  desirable  for  reasons  of  cost,  labor  attached 
to  working  it  and  conductivity  of  heat,  therefore  heads  must  be  of 
less  thickness  and  bracing  resorted  to. 

To  find  the  area  of  an  unstayed  segment  is  the  first  thing  neces- 
sary and  that  is  a  simple  rule  as  used  in  boiler  construction,  as 
calculations  for  such  measures  are  always  favored. 


Rule  to  find  minimum  area  of  stay  or  brace  to  support  a  given 
area:  Divide  load  on  stay  by  allowable  strain  per  square  inch  of 
sectional  area  as  provided ;  the  quotient  is  minimum  area  of  stay. 

FORMULA: 

L 

—  =area  of  brace 
S 
LEGEND: 

L  =  load  on  stay  =6750  Ibs. 

S  =strain  per  square  inch  of  sectional  area  =6000  Ibs. 


BRACES  AND  REINFORCING.  83 

EXAMPLE: 

strain  allowed  per  sq.  in.  =6000)6750 . 000(1 . 125  or  \y%'  diameter 

6000 


750  0 
600  0 

150  00 

120  00 


300  00 
300  00 


Rule  to  find  area  of  stay  beyond  maximum  of  curved  surface 
unsupported  when  thickness  of  plate  and  pressure  are  known :  Mul- 
tiply constant  112  by  thickness  of  plate  in  sixteenths  of  an  inch  and 
divide  product  by  the  pressure  in  pounds  per  square  inch;  the 
quotient  is  area  of  stay  required. 

LEGEND:  FORMULA: 

C  =  constant  =  112  CxT 

T  =  thickness  of  plate  =  Tg  —  =area  of  stay 

P  =  pressure  =  150  Ibs.  P 

EXAMPLE: 

112  =  constant 
.  7  =  thickness  in  16ths 


pressure  =  150) 78.  4000 (.  5226  =area  or  |£  approximately 
75  0 

3  40 
3  00 

400 
300 


1000 
900 

100 

To  determine  the  areas  of  diagonal  stays :  Multiply  the  area  of 
a  direct  stay  required  to  support  the  surface  by  the  slant  or  diagonal 
length  of  the  stay ;  divide  this  product  by  the  length  of  a  line  drawn 
at  right  angles  to  surface  supported  to  center  of  palm  of  diagonal 
stay.  The  quotient  will  be  the  required  area  of  the  diagonal  stay. 

FORMULA: 
AXL 

—  =  sectional  area  of  diagonal  stay 


84  THE  BOILER. 

LEGEND: 

A  =  sectional  area  of  direct  stay  =  .  7854 
L  =length  of  diagonal  stay  =60" 

1=  length  of  line  drawn  at  right  angles  to  boiler  head  or  surface 
supported  to  center  of  palm  of  diagonal  stay  =  48" 

EXAMPLE: 

.7854    =area  of  1"  direct  stay 

60  =  length  of  stay 
length  of  line  drawn  at  right 

angles  to  boiler  =  48") 47. 1240 (.  9817  =sectional  area  of  a  diag- 
43  2  onal  brace  =  1^"   nearly 

3  92 
3   84 


84 
48 

360 
336 

24 

When  diagonal  braces  are  applied  the  angle  should  not  exceed 
over  30  degrees. 

Rule  to  find  the  load  on  a  stay :     Multiply  area  to  be  supported 
by  pressure  and  divide  by  sectional  area  of  stay  bolt. 
LEGEND:  FORMULA: 

A    =  area  to  be  supported  =50"  AxP 

P     =pressure  =  160  Ibs.  —  =strain  on  sectional  area 

SB  =area  of  stay  bolt  =  .  69029  SB  of  stay 

EXAMPLE: 

50"  =area  to  be  supported 

160=  pressure 

3000 
50 


area  of  stay  bolt  =  .69029)8000.00000(11589  Ibs.  =strain  on  sec- 
6902  9  tional  area  of  stay 


1097  10 
690  29 

406  810 
345  145 

61  6650 
55  2232 


6  44180 
6  21261 

22919 


BRACES  AND  REINFORCING.  85 

HEADS. 

All  heads  employed  in  the  construction  of  cylindrical  externally 
fired  boilers,  for  steamers  navigating-  the  Red  River  of  the  North  and 
rivers  that  flow  into  the  Gulf  of  Mexico,  shall  have  a  thickness  of 
material  as  follows : 

For  boilers  having  a  diameter — - 

Over  32  inches  and  not  over  36  inches,  not  less  than  1^  inch. 
Over  36  inches  and  not  over  40  inches,  not  less  than  ^  inch. 
Over  40  inches  and  not  over  48  inches,  not  less  than  ^  inch. 
Over  48  inches,  not  less  than  %  inch. 

Where  flat  heads  do  not  exceed  20  inches  in  diameter  they  may 
be  used  without  being  stayed,  and  the  steam  pressure  allowable  shall 
be  determined  by  the  following  formula : 

CxT2 
P= 


Where  P  =  steam  pressure  allowable  in  pounds. 

T  =  thickness  of  material  in  sixteenths  of  an  inch. 
A  =  one-half  the  area  of  head  in  inches. 
C  =  112  for  plates  -fa  of  an  inch  and  under. 
C  =  120  for  plates  over  fa  of  an  inch. 

Provided,  The  flanges  are  made  to  an  inside  radius  of  at  least 
\l/2  inches. 

EXAMPLE. 

Required  the  working  pressure  of  a  flat  head  20  inches  in  diame- 
ter and  y^  of  an  inch  thick.  Substituting  values,  we  have 

120X144 

P  =  —  —=110  pounds 

157 

The  heads  of  steam  and  mud  drums  of  such  boilers  shall  have 
a  thickness  of  material  of  not  less  than  half  an  inch ;  pressure  to  be 
determined  by  formula  for  flatheads. 


86  THE  BOILER. 

CONVEXED   HEAD. 

Rule  to  find  pressure  allowed  on  a  convexed  head :  Multiply  the 
thickness  of  the  plate  by  one-sixth  of  the  tensile  strength  and  divide 
by  one-half  of  radius  to  which  head  is  bumped ;  result  gives  pressure 
allowed  per  square  inch. 

Add  20  per  cent  to  pressure  when  the  head  is  double  riveted  to  the  shell 
and  the  holes  are  fairly  drilled. 

LEGEND:  FORMULA: 

TS  =  tensile  strength  =60000  T  X  ( 1/6  of  TS ) 

T  =  thickness  of  plate  =  ^  =  .  625  =lbs.    pressure   al- 

R=radius  of  bump  =60"  }/%  of  R  lowed 

EXAMPLE  : 

.  625  =  thickness  of  plate 
10000  =  1/6  of  TS 


half  of  radius  =30)6250.p00  (208  Ibs.  =  pressure  allowed  on  single 
60  riveted  circumferential  seam 


250 
240 

10 

208  Ibs.  =  pressure  allowed  on  single  riveted 
41.6=  20%  added  for  double  riveted 


249 .  6  Ibs.  pressure  allowed  double  riveted 

Rule  to  find  bursting  pressure  on  flat  head :  Multiply  thickness 
of  plate  by  ten  times  the  tensile  strength  and  divide  by  area  of  head 
in  inches ;  the  sum  is  bursting  pressure. 

LEGEND:  FORMULA: 

T    =  thickness  of  plate  =  &  =  .5625  Tx(lOXTS) 

TS  =tensile  strength  =60000  —  =bursting  pressure 

A    =  area  of  head  =934.  822  inches  AxC 

D    =  diameter  of  head  =34^" 

EXAMPLE: 

.  5625  =  thickness  of  plate 

600000  =ten  times  tensile  strength 

area  of  head  =934822)337500.  0000  (361  Ibs.  bursting  pressure 
280446  6 


57053  40 
56089  32 

964  080 
934  822 

29  258 
Divide  bursting  pressure  by  5  and  this  will  give  working  pressure 


BRACES  AND  REINFORCING. 


87 


CONCAVED  HEAD. 

Rule  to  find  pressure  allowed  on  a  concave  head :  Multiply  the 
pressure  per  square  inch  allowed  on  a  bumped  head  attached  con- 
vexly  by  the  constant  6,  and  the  product  will  give  the  pressure  per 
square  inch  allowed  on  concaved  head. 


LEGEND: 


FORMULA: 

P  XC  = pressure  on  concaved  head 


P=  pressure  allowed  on  a  bumped  head  =208  Ibs. 
C  =  constant  =.6 

EXAMPLE: 


208  =  pressure  allowed  on  a  bumped  head 
.6  =  constant 


124.8  =lbs.    pressure  on  a  concaved  head 


NOTE  ON  DISHED  HEADS. 

Dished  or  bumped  heads  have  strength  due  to  form  and  thickness 
depending  on  diameter. 

Bumped  heads  may  contain  a  manhole  opening  flanged  inwardly, 
when  such  flange  is  turned  to  a  depth  of  three  times  the  thickness 
of  the  material  in  the  head. 


DEPTHS  OF  DISH  AND  FLANGE  HEADS. 


Diam.  after 

Diam.  Heads. 

Dishing  and 
Flanging. 

Depth 
of  Dish. 

Depth 
of  Flange. 

34 

30 

3 

2 

40 

36 

3 

2 

46 

42 

4 

2 

52^ 

48 

5 

2 

58^ 

54 

6 

2 

65 

60 

6 

2 

71 

66 

7 

2 

77 

71^ 

7 

2 

78 

72 

8 

2 

87 

80 

8 

2-L/ 

91 

84 

9 

2^ 

97 

90 

10 

2  J^> 

102 

96 

12 

2J*| 

88 


THE  BOILER. 


CAST  IRON  HEADS. 

Rule  to  find  thickness  of  an  unstayed  boiler  head  so  it  will  equal 
in  strength  the  shell  :  Multiply  square  root  of  radius  by  the  thick- 
ness of  the  shell  plate  in  inches  ;  the  product  is  the  required  thickness 
of  head. 

LEGEND:  FORMULA: 

T=thickness  of  plate  %,"  =  .375  (\/IR)  XT=thicknessof  head 

IR  =inside  radius  =  19  .  9809 

EXAMPLE: 

4.47  =square  root  of  radius 
.375  =  thickness  of  shell 


2235 
3129 
1341 


1.67625  =  thickness  of  head  required  =1^"  approx. 

A  rule"  to  find  area  of  a  segment  of  a  circle  as  outlined  by  A,  B 
and  C. 


Divide  the  diameter  of  circle  by  height  of  the  segment,  subtract 
608  from  quotient  and  extract  the  square  root  of  the  remainder; 
this  result  multiplied  by  four  times  the  square  of  the  height  of  the 
segment  and  divided  by  three,  will  give  the  area. 

FORMULA: 

f  V  D  ~r      f  4XHM 

•{ .  608  >•  X  •{ r  =  area  of  segment 

1        H  J       I       3      J 


BRACES  AND  REINFORCING.  89 


LEGEND: 

H  =  height  of  segment  22" 
D  =diam.  of  boiler  72" 
C=  constant  =  .608 

EXAMPLE: 
(diameter) 
height  22") 72. 0000 (3.  2727 


66 


60 

44 

3.2727 


160  . 608  constant 


1)2.66470000(1.6323  sq.  root 
154  1 

60  26   1  66  1.6323 

44  1  56  645 


160        323   1047        8  1615 
154  969       65  292 

979  38 

6       3262     7800 

22"  height  of  segment  6524          1052 . 8335 

22  or  1053"=area  of 

32643  127600  segment. 

44  97929 

44 

29671 

484  height  squared 
4  four  times 


3)  1936  =4  times  square  of  height 
645.33 


Rule  to  find  number  of  braces  to  support  a  segment  as  just 
described:  Multiply  area  of  segment  by  pressure  in  pounds  per 
square  inch  and  divide  by  number  of  pounds  pressure  form  or  type 
of  brace  sectional  area  is  allowed.  To  illustrate :  A  modern  formed 
brace  by  8,000  when  sectional  area  exceeds  5  square  inches ;  7,000 
when  sectional  area  is  less  than  5  square  inches,  and  6,000  for  all 
stays  not  otherwise  provided  for. 

FORMULA: 

A  X  Pressure 

—  =  number  of  braces  required 
Brace  supporting  value 


90  THE  BOILER. 


EXAMPLE: 


1053  =area  of  segment  required 
160  =lbs.  pressure 

63180 
1053 


modern  brace  =8000)168480(21  +  or  22  braces 
16000 


8480 
8000 


480 

The  table  given  below  is  an  extract  from  Trautwine's  Engineers' 
Pocket  Book,  and  will  be  found  of  great  value  in  arriving  at  an 
accurate  solution. 

The  first  column  marked  height,  is  the  height  of  the  segment  in 
parts  of  the  diameter  of  the  boiler.  The  first  number  .001  refers  to 
a  segment  whose  height  is  1/1000  of  the  diameter  of  the  boiler,  the 
second  number  refers  to  2/1000  of  the  diameter  of  the  boiler,  and 
the  third  3/1000  of  the  diameter  of  the  boiler  and  so  on  until  it 
reaches  a  complete  semi-circle  or  half-diameter  of  the  boiler. 

CUBICAL    CONTENTS. 

Suppose  now  we  desire  to  find  the  cubical  contents  by  the  table 
of  the  steam  space  in  a  boiler  48  inches  in  diameter  by  14  feet  long. 
The  water  line  say  is  4"  above  the  top  row  of  tubes  and  the  height 
of  the  segment  is  12  inches. 

The  area  of  circles  or  similar  parts  of  circles  of  different  sizes 
are  directly  proportional  to  the  square  of  their  diameter.  Hence,  it 
will  only  be  necessary  to  find  what  part  of  the  diameter,  12  inches 
(the  height  of  the  steam  space),  is.  This  is  done  by  dividing  12 
by  48  =  .250.  Find  this  quotient  in  the  column  of  heights  in  the 
table,  take  the  corresponding  area  and  multiply  it  by  the  square  of 
the  diameter.  Then  4X4  equals  16  and  12-^-48  equals  .250.  By 
the  table  we  find  that  the  area  of  a  segment  whose  height  is  .250 
is  seen  to  be  .153546.  This  multiplied  by  16  gives  2.4567  square 
feet  of  the  cross  sectional  area  of  the  steam  space.  This  area  multi- 
plied by  14,  which  is  the  length  of  the  boiler  in  feet,  or  2.4567  X  14 
equals  34.39,  which  is  the  volume  of  steam  space  in  cubic  feet. 

The  same  result  in  cubic  feet  can  be  obtained  by  the  first  method, 
which  I  do  not  think  can  be  simplified  any  further. 


BRACES  AND  REINFORCING. 


91 


AREAS  OF  CIRCULAR  ARCS. 
By  This  Table  May  be  Obtained  the  Area  of  Segments  of  Circles. 


Height 

Area 

Height 

Area 

Height 

Area 

Height 

Area 

.001 
.002 
.003 

.000  042 
.000  119 
.000  219 

.040 
.041 
.042 

.010  538 
.010  932 
.011  331 

079 
.080 
.081 

.028  894 
.029  435 
.029  979 

.118 
.119 
.120 

.052  090 
.052  737 
.053  385 

.004 
.005 
.006 

.000  337 
.000  471 
.000  619 

.043 

.044 
.045 

.011  734 
.012  142 
.012  555 

.082 
.083 
.084 

.030  526 
.031  077 
.031  630 

.121 
.122 
.123 

.054  037 
.054  690 
.055  346 

.007 
.008 
.009 

.000  779 
.000  952 
.001  135 

.046 
.047 
.048 

.012  971 
.013  393 
.013  818 

.085 
.086 
.087 

.032  186 
.032  746 
.033  308 

.124 
.125 
.126 

.056  004 
.056  664 
.057  327 

.010 
.011 

.012 

.001  329 
.001  533 
.001  746 

.049 
.050 
.051 

.014  248 
.014  681 
.015  119 

.088 
.089 
.090 

.033  873 
.034  441 
.035  012 

.127 
.128 
.129 

.057  991 
.058  658 
.059  328 

.013 
.014 
.015 

.001  969 
.002  199 
.002  438 

.052 
.053 
.054 

.015  561 
.016  008 
.016  458 

.091 
.092 
.093 

.035  586 
.036  162 
.036  742 

.130 
.131 
.132 

.059  999 
.060  673 
.061  349 

.016 
.017 
.018 

.002  685 
.  002  940 
.  003  202 

.055 
.056 
.057 

.016  912 
.017  369 
.017  831 

.094 
.095 
.096 

.037  324 
.037  909 
.038  497 

.133 
.134 
.135 

.062  027 
.062  707 
.063  389 

.019 
.020 
021 

.003  472) 
.003  749 
004  032 

.058 
.059 
.060 

.018  297 
.018  766 
.019  239 

.097 
.098 
.099 

.039  087 
.039  681 
.040  277 

.136 
.137 
.138 

.064  074 
.064  761 
.065  449 

.022 
.023 
.024 

.004  322 
.004  619 
.004  922 

.061 
.062 
.063 

.019  716 
.020  197 
.020  681 

.100 
.101 
.102 

.040  875 
.041  477 
.042  081 

.139 
.140 
.141 

.066  140 
.066  833 
.067  528 

.025 
.026 
.027 

.005  231 
.005  546 
.005  867 

.064 
.065 
.066 

.021  168 
.021  660 
.022  155 

.103 
.104 
.105 

.042  687 
.043  296 
.  043  908 

.142 
.143 
.144 

.068  225 
.068  924 
.069  626 

.028 
.029 
.030 

.006  194 
.006  527 
.006  866 

.067 
.068 
.069 

.022  653 
.023  155 
.  023  660 

.106 
.107 
.108 

.044  523 
.045  140 
.045  759 

.145 
.146 
.147 

.070  329 
.071  034 
.071  741 

.031 
.032 
.033 

.007  209 
.007  559 
.007  913 

.070 
.071 
.072 

.024  168 
.024  680 
.025  196 

.109 
.110 
.111 

.046  381 
.047  006 
.047  633 

.148 
.149 
.150 

.072  450 
.073  162 
.073  875 

.034 
.035 
.036 

.008  273 
.008  638 
.009  008 

.073 

.074 
.075 

.025  714 
.026  236 
.026  761 

.112 
.113 
.114 

.048  262 
.048  894 
.049  529 

.151 
.152 
.153 

.074  590 
.075  307 
.076  026 

.037 
.038 
.039 

.009  383 
.009  764 
.010  148 

.  .076 
.077 
.078 

.027  290 
.027  821| 
.028  356| 

.115 
.116 
.117 

.050  165 
.050  805 
.051  446 

.154 
.155 
.156 

.076  747 
.0^7  470 
.078  194 

92 


THE  BOILER. 


Height 

Area 

Height 

Area 

Height 

Area 

Height 

Area 

.157 
.158 
.159 

.078  921 
.079  650 
.080  380 

.199 
.200 
.201 

.111  025 
.111  824 
.112  625 

.241 
.242 
.243 

.  145  800 
.146  656 
.147  513 

.281 
.282 
.283 

.180  918 
.181  818 
.182  718 

.160 
.161 
.162 

.081  112 
.081  847 
.082  582 

.202 
.203 
.204 

.113  427 
.114  231 
.115  036 

.244 
.245 
.246 

.148  371 
.149  231 
.150  091 

.284 
.285 
.286 

.183  619 
.184  522 
.185  425 

.163 
.164 
.165 

.083  320 
.084  090 
.084  801 

.205 
.206 
.207 

.115  842 
.116  651 
.117  460 

.247 
.248 
.249 

.150  953 
.151  816 
.152  681 

.287 
.288 
.289 

.186  329 
.187  235 
.188  141 

.166 
.167 
.168 

.085  545 
.086  200 
.087  037 

.208 
.209 
.210 

.118  271 
.119  084 
.119  898 

.250 

.153  546 

.290 
.291 
.292 

.189  048 
.189  956 
.190  865 

.169 
.170 
.171 

.087  785 
.088  536 
.089  288 

.211 
.212 
.213 

.120  713 
.121  530 
.122  348 

.251 
.252 
.253 

.154  413 
.155  281 
.156  149 

.293 
.294 
.295 

.191  774 
.192  685 
.193  597 

.172 
.173 
.174 

.  090  042 
.090  797 
.091  555 

.214 
.215 
.216 

.123  167 
.123  988 
.124  811 

.254 
.255 
.256 

.157  019 
.157  891 
.158  763 

.296 
.297 
.298 

.194  509 
.  195  423 
.196  337 

.175 
.176 
.177 

.092  314 
.093  074 
.093  837 

.217 
.218 
.219 

.125  634 
.126  459 
.127  286 

.257 
.258 
.259 

.159  636 
.160  511 
.161  386 

.299 
.300 
.301 

.197  252 
.198  168 
.199  085 

.178 
.179 
.180 

.094  601 
.095  367 
.096  135 

.220 
.221 
.222 

.128  114 
.  128  943 
.129  773 

.260 
.261 
.262 

.162  263 
.163  141 
.164  020 

.302 
.303 
.304 

.200  003 
.200  922 
.201  841 

.181 
.182 
.183 

.096  904 
.097  675 
.098  447 

.223 
.224 
.225 

.  130  605 
.131  438 
.132  273 

.263 
.264 
.265 

.  164  900 
.165  781 
.166  663 

.305 
.306 
.307 

.202  762 
.203  683 
.  204  605 

.184 
.185 
.186 

.099  221 
.099  997 
.  100  774 

.226 
.227 
.228 

.  133  109 
.133  946 
.  134  784 

.266 
.267 
.268 

.167  546 
.168  431 
.169  316 

.308 
.309 
.310 

.205  528 
.206  452 
.207  376 

.187 
.188 
.189 

.101  553 
.102  334 
.103  116 

.229 
.230 
.231 

.135  624 
.136  465 
.137  307 

.269 
.270 
.271 

.170  202 
.171  090 
.171  978 

.311 
.312 
.313 

.208  302 
.209  228 
.210  155 

.190 
.191 
.192 

.  103  900 
.104  686 
.105  472 

.232 
.233 
.234 

.138  151 
.138  996 
.  139  842 

.272 
.273 
.274 

.172  868 
.173  758 
.174  650 

.314 
.315 
.316 

.211  083 
212  Oil 
212  941 

.193 
.194 
.195 

.106  261 
.107  051 
.  107  843 

.235 
.236 
.237 

.140  689 
.141  538 
.142  388 

.275 
.276 
.277 

.175  542 
.176  436 
177  330 

.317 
.318 
.319 

213  871 
214  802 
215  734 

.196 
.197 
.198 

.108  636 
.109  431 
.110  227 

.238 
.239 
.240 

.  143  239 
.144  091 
.  144  945 

.278 
.279 
.280 

.178  226 
.179  122 
.180  020 

.320 
.321 
.322 

216  666 
217  600 
218  534 

BRACES  AND  REINFORCING. 


93 


Height 

Area 

Height 

Area 

Height 

Area 

Height 

Area 

.323 
.324 
.325 

.219  469 
.220  404 
.221  341 

.368 
.369 
.370 

.262  249 
.263  214 
.264  179 

.413 
.414 
.415 

.306  140 
.307  125 
.308  110 

.458 
.459 
.460 

.350  749 
.351  745 
.352  742 

.326 
.327 
.328 

.222  278 
.223  216 
.224  154 

.371 
.372 
373 

.265  145 
266  111 
.267  078 

.416 
.417 
.418 

.309  096 
.310  082 
.311  068 

.461 
.462 
.463 

.353  739 
.354  736 
.355  733 

.329 
.330 
.331 

.225  094 
.226  034 
.226  974 

.374 
.375 
.376 

.268  046 
.269  014 
.269  982 

.419 
.420 
.421 

.312  055 
.313  042 
.314  029 

.464 
.465 
.466 

.356  730 
.357  728 
.358  725 

.332 
.333 
.334 

.227  916 
.228  858 
.229  801 

.377 
.378 
.379 

.270  951 
.271  921 
.272  891 

.422 
.423 
.424 

.315  017 
.316  005 
.316  993 

.467 
.468 
.469 

.359  723 
.360  721 
.361  719 

.335 
.336 
.337 

.230  745 
.231  689 
.232  634 

.380 
.381 
.382 

.273  861 
.274  832 
.275  804 

.425 
.426 
.427 

.317  981 
.318  970 
.319  959 

.470 
.471 
.472 

.362  717 
.363  715 
.364  714 

.338 
.339 
.340 

.233  580 
.234  526 
.235  473 

.383 
.384 
.385 

.276  776 
.277  748 
.278  721 

.428 
.429 
.430 

.320  949 
.321  938 
.322  928 

.473 
.474 
.475 

.365  712 
.366  711 
.367  710 

.341 
.342 
.343 

.236  421 
.237  369 
.238  319 

.386 
.387 
.388 

.279  695 
.280  669 
.281  643 

.431 
.432 
.433 

.323  919 
.324  909 
.325  900 

.476 
.477 
.478 

.368  708 
.369  707 
.370  706 

.344 
.345 
.346 

.239  268 
.240  219 
.241  170 

.389 
.390 
.391 

.282  618 
.283  593 
.284  569 

.434 
.435 
.436 

.326  891 
.327  883 
.328  874 

.479 

.480 
.481 

.371  705 
.372  704 
.373  704 

.347 
.348 
.349 

.242  122 
.243  074 
.244  027 

.392 
.393 
.394 

.285  545 
.286  521 
.287  499 

.437 
.438 
.439 

.329  866 
.330  858 
.331  851 

.482 
.483 
.484 

.374  703 
.375  702 
.376  702 

.350 

.351 
.352 

.244  980 
.245  935 
.246  890 

.395 
.396 
.397 

.288  476 
.289  454 
.290  432 

.440 
.441 
.442 

.332  843 
.333  836 
.334  829 

.485 
.486 
.487 

.377  701 
.378  701 
.379  701 

.353 
.354 
.355 

.247  845 
.248  801 
.249  758 

.398 
.399 
.400 

.291  411 
.292  390 
.293  370 

.443 

.444 
.445 

.335  823 
.336  816 
.337  810 

.488 
.489 
.490 

.380  700 
.381  700 
.382  700 

.356 

.357 
.358 

.*250  715 
.251  673 
.252  632 

.401 
.402 
.403 

.294  350 
.295  330 
.296  311 

.446 
.447 
.448 

.338  804 
.339  799 
.  340  793 

.491 
.492 
.493 

.383  700 
.384  699 
.385  699 

.359 
.360 
.361 

.253  591 
.254  551 
.255  511 

.404 
.  105 
.406 

.297  292 
.298  274 
.299  256 

.449 
.450 
.451 

.341  788 
.342  783 
.343  778 

.494 
.495 
.496 

.386  699 
.387  699 
.388  699 

.362 
.363 
.364 

.256  472 
.257  433 
.258  395 

.407 
.408 
.409 

.300  238 
.301  221 
.302  204 

.452 
.453 
.454 

.344  773 
.345  768 
.346  764 

.497 
.498 
.499 

.389  699 
.390  699 
.391  699 

.365 
.366 
.367 

.259  358 
.260  321 
.261  285 

.410 

.411 
.412 

.303  187 
.304  171 
.305  156 

.455 
.456 
,457 

.347  760 
.348  756 
.349  752 

.500 

.392  699 

94  THE  BOILER. 

Rule  to  find  pressure  allowed  on  a  brace  for  given  size :  Multiply 
area  of  brace  by  pressure  allowed  per  square  inch  cross  sectional 
area. 

LEGEND:  FORMULA: 

A  =  area  of  brace  3"x^"  =1.5"  area  AxS=pressure  allowed 

S  =strain  allowed  =  6000  Ibs. 
that  size  brace 

EXAMPLE: 
3" 
.5 

1.5=  area 

6000  Ibs.  allowed  per  square  inch 

9000J3  Ibs.  allowed  on  brace  of  that  size 


THROUGH  BRACE  RODS. 

Through  brace  rods  are  often  used  when  conditions  are  favor- 
able, space  ample  for  cleaning  and  inspection. 

These  rods  are  usually  1^4  to  2^/2  inches  diameter  and  washer 
or  plates  riveted  to  heads  to  increase  holding  or  breaking  surface ; 
thickness  of  heads  are  governed  by  pressure,  also  by  the  size  and 
number  of  rods.  Same  rule  is  used  that  governs  the  palm  or  formed 
brace. 

Rule  to  find  working  pressure  allowed  on  a  through  brace  rod. 
Multiply  area  of  rod  by  strain  allowed  according  to  corresponding 
diameter  and  divide  by  area  supported  by  rod. 

LEGEND:  FORMULA: 

AR=  2"  rod  =3. 1416=  area  of  rod  ARxS 

A  =  16x14  surface  =224"  area  —  =working  pressure 

S  =  strain  allowed  on  that  size  A 

brace  =  8000 

EXAMPLE: 
3.1416=area  of  2"  rod 

8000  Ibs.  allowed  on  sectional  area 


surface  area  =224)25132. #000 (112  Ibs.  working  pressure 
224 

273 
224 

492 
448 

44 


BRACES  AND  REINFORCING.  95 

CURVED  SURFACES. 

To  find  safe  working  pressure  on  curved  sufrace  when  stiffened 
by  angle,  single  or  double,  or  tee  bars ;  for  single,  the  angle  iron 
should  have  a  thickness  of  at  least  eight-tenths  that  of  plate  and  a 
depth  of  at  least  one-half  pitch ; — where  stiffened  with  double  angle 
or  tee  irons,  to  have  at  least  two-thirds  that  of  thickness  of  plate 
and  a  depth  of  at  least  one-fourth  of  pitch ;  angles  or  tee  bars  being 
substantially  riveted  to  the  plate  supported. 

Where  rounded  tops  of  combustion  chambers  are  stiffened  with 
single  or  double  angle-iron  stiffeners,  or  tee  bars,  such  angles  or  tee 
bars,  shall  be  of  thickness  and  depth  of  leaf  not  less  than  specified 
for  rounded  bottoms  of  combustion  chambers.  Said  angles  or  tee 
bars  shall  be  supported  on  thimbles  and  riveted  through  with  rivets 
not  less  than  one  inch  in  diameter  and  spaced  not  to  exceed  six 
inches  between  centers. 

Rule  to  find  working  pressure  allowed  on  rounded  surfaces  sup- 
ported by  angle  irons  or  tee  bars:  Multiply  constant  by  thickness 
squared  in  sixteenths  and  divide  by  the  pitch  multiplied  by  the 
diameter  of  curve. 

FORMULA: 

CxT2 

—  =  working  pressure 
PXD 

LEGEND: 

T  =  thickness  of  plate  in  sixteenths  of  an  inch  =  &  =  81 

P  =  pitch  of  angle  or  tee  stiffeners  in  inches  =  7  inches 

D  =  diameter  of  curve  to  which  plate  is  bent,  in  inches  =51  inches 

C  =  constant  =  900 

EXAMPLE: ^ 

900  =  constant  51"  =diameter 

81  =  thickness  squared  in  16ths  7"  =  pitch 

900  357 

7200 


72900  714 

1500 
1428 

72 


357)72900(204  Ibs.  =  working  pressure 


96  THE  BOILER. 

TUBE  PLATE 

Rule  to  find  the  working  pressure  of  a  tube  sheet  supporting  a 
crown  sheet  braced  by  crown  bars:  Subtract  inside  diameter  of 
tubes  in  inches  from  the  least  horizontal  distance  between  tube  cen- 
ters in  inches ;  multiply  the  remainder  by  thickness  of  tube  plate  and 
then  by  constant  27,000;  divide  product  by  extreme  width  of  com- 
bustion chamber  multiplied  by  least  horizontal  distance  between 
tube  centers. 

FORMULA: 

(D— d)TxC 

—  =  working  pressure 
WXD 

LEGEND: 

D  =least  horizontal  distance  between  tube  centers  in  inches  =  4^  inches 
d  =inside  diameter  of  tubes  in  inches  =  2  .  782  inches 
T  = thickness  of  tube  plate  in  inches  =^  inches  =  .  6875 
W  ^extreme  width  of  combustion  chamber  in  inches  =34*4  inches 
C  =27,000. 

EXAMPLE: 

4. 125  =  least  horizontal  distance 
2  .  782  =  inside  diameter 

1.343 

.6875  =  thickness  of  tube  plate 


6715 
9401 

10744  34. 25=  extreme  width 

8058  4 . 125  =  least  horizontal  distance 

.9233125  17125 

2  7000=  constant  6850 

3425 

646  31875000  13700 
1846  6250 


141. 
24929.  ^3WP0 

141)24929(176  Ibs.  =  working  pressure 
141 

1082 
987 

959 
846 

113 


BRACES  AND  REINFORCING.  97 

Rule  to  find  thickness  of  plate  for  a  tube  sheet :  Multiply 
pressure  by  width  of  fire  box  and  by  pitch  of  tubes  (distance 
between  centers)  and  divide  this  sum  by  pitch  of  tubes  minus  one 
inside  diameter  of  one  tube  multiplied  by  constant. 


FORMULA: 
PxWxp 
(p— d)xC 
LEGEND: 


=  thickness  of  plate 


p    =  pitch  of  tube  =4^ 

d    =  inside  diam.  of  tube  =2.  7 82 

P  =  pressure  =  176  Ibs. 

C   =  constant  =2  7000 

W  =  width  of  combustion  chamber  =34)4  inches 

EXAMPLE: 


176  =  pressure  Ibs.  per  square  inch 
34.25  =  width  of  fire  box 


880 
352 
704 
528 

pitch  of  tubes  =4. 12 5 
inside  diam.  =2.782  6028.00 

4. 12 5=  pitch  of  tubes 


1.343 


constant  =   27000    3014000 

1205600 

9401000   602800 
2686     2411200 


36261000)24865.  5000  (.6857  or  ft  nearly 
217566 


310890 
290088 


208020 
181305 

267150 
253827 

13323 


98  THE  BOILER. 

U.  S.  RULES. 

The  compressive  stress  on  tube  plates,  as  determined  by  the 
following  formula,  must  not  exceed  13,500  pounds  per  square  inch, 
when  pressure  on  tops  of  combustion  chamber  is  supported  by 
vertical  plates  of  such  chamber. 

PxDxW 

—  =  compressive  stress 
2X(D— d)XT 

P  =  working  pressure  in  pounds  =  176  Ibs. 

D  =least  horizontal  distance  between  tube  centers  in  inches  =4. 1250" 
d  =inside  diameter  of  tube  in  inches  =2  .  782. 
W  =  extreme  width  of  combustion  chamber  in  inches  =34^ 
T  =  thickness  of  tube  sheet  in  inches  =^  =  .  6875. 

EXAMPLE: 

176    =  pressure 
4. 1250=distance  tubes  horizontally 

8800 
352 
176 
704 


726.0000 

34 . 25  =  width  of  combustion  chamber 


36300000  4. 1250  =dis. bet.  tubes 

14520000  2.782    =inside  diam.  tube 

29040000 
21780000  1.3430 

2  =  twice 
1.84662500)24865.  50000000  (13465  =compres-  - 

184662500  sive  strain     2.6860 

.6875=^  =  thickness  of 

6399  25000  tube  sheet 

5539  87500  134300 

188020 

859  375000  214880 

738  650000  161160 


120  7250000  1.84662500 

110  7975000 


9  92750000 
9  23312500 

69437500 

Sling  stays  may  be  used  in  lieu  of  girders  in  all  cases,  provided, 
however,  that  when  such  sling  stays  are  used,  girders  or  screw 
stays  of  the  same  sectional  area  must  be  used  for  securing  the 
bottom  of  combustion  chamber  to  the  boiler  shell. 


BRACES  AND  REINFORCING.  99 


Rule  to  find  thickness  of  steel  girder :  From  length  of  girder  sub- 
tract pitch  of  bolts  and  multiply  by  centers  of  girders  and  by  length 
of  same  and  this  sum  by  pressure;  divide  this  product  by  depth  of 
girder  squared  multiplied  by  constant  and  then  multiplied  by  the 
square  root  of  number  of  supporting  bolts. 

FORMULA: 

(L— P)XGXLXP 

—  =  thickness  of  girder  required. 
d2xCX\/N 

LEGEND: 

L  =  length  of  girder  =  32" 
P  =pitch  of  bolts  =9" 
G  =  girder  centers  =  8  3^" 
d  =  depth  of  girder  =  5.18" 
C=  constant  =6000 
N  =  number  of  bolts  =9 

EXAMPLE: 

32 . 000"  =  length  of  girder 
9 . 000"  =  pitch  of  bolts 

23.000" 

8 .  5"  =girder  centers 


115000 
184000 
depth  of  girders  =5.18 


5.18  195.5000 

32"  =  length  of  girder 
4144 

518  3910000 

2590  5865000 


26.8324  6256.0000 

constant  =  6000  160=pressure 


160994.4000  3753600000 
sq.  rt.  of  bolts  =   3    62560000 


4829832000)  1000960000  (2 .  0  =  thickness  of  girder 
965966 


349940 


100  THE  BOILER. 

In  connection  with  rules  covering  girder  calculations  there  are 
constants  used  and  varying  according  to  plate  thickness  and  design  of 
bolt,  such  as  screwed  stayed  bolts  with  and  without  lock  nuts, 
sockets,  with  riveted  heads,  number  of  bolts  and  water  used,  as 
follows : 

Use  constant  5400  for  roof  stays,  wrought  iron. 
Use  constant  6000  for  roof  stays,  steel. 

A  constant  used  by  Joshua  Rose  for  computing  girder  or  crown 
bar  supporting  bolts  9000  (this  for  steel). 


Rule  to  find  area  of  supporting  bolts  (steel)  for  a  girder  stay  or 
crown  bar.  Multiply  pressure  by  area  to  be  supported  and  divide 
this  product  by  constant  9000,  this  will  give  the  pounds  strain 
allowed  per  square  inch  of  sectional  area  for  a  mild  steel  bolt. 

FORMULA: 

AXP 

—  =        afea    supporting  bolt  required 


LEGEND: 

A  =area  to  be  supported  =8"  X  8"  =  64  square  inches 
P  =  pressure  =  170  Ibs. 
C=  constant  =9000 


EXAMPLE: 


64=  square  inches  to  be  supported 
170=  pressure 


4480 
64 


constant  =  9000)  10880 .  0000  (1 .  2088  =area  =  1  ^  approximately 
9000 


1880  0 
1800  0 

800  00 
720  00 

80  000 
72  000 

8  000 


BRACES  AND  REINFORCING.  101 

Rule  to  find  safe  working  pressure  on  a  girder  supporting  a 
crown  sheet  of  a  back  smoke  box  connection,  when  not  subjected  to 
heat  in  excess  of  ordinary  steam  pressures  and  assuming  the  com- 
bustion chamber  ends  are  fitted  to  the  edge  of  tube  plate  and  the 
back  of  plate  of  the  combustion  box,  four  supporting  bolts  being 
used.  Multiply  constant  by  depth  of  girder  squared  in  inches  and 
multiply  this  sum  by  thickness  of  girder  in  inches;  divide  product 
by  width  of  combustion  chamber  in  inches  minus  pitch  of  supporting 
bolts  multiplied  by  distance  between  girders  from  center  to  center 
in  inches  and  again  by  length  of  girder  in  feet. 

FORMULA: 
:  Cxd2XT 


=  pressure 

(W— P)XDXL 

LEGEND: 

W  =  width  of  combustion  box  in  inches  =  36" 
P  =  pitch  of  supporting  bolts  in  inches  =7^=7.5 
D  =  distance  between  girder  centers  in  inches  =7%  =7.  75 
L  = length  of  girder  in  feet  =3  feet  =3 
d  =  depth  of  girder  in  inches  =  7^=7.5 
T  =  thickness  of  girder  in  inches  =2"  =  2 
C  =  constant 


=  550 — when  girder  is  fitted  with  one  supporting  bolt 
825 —  two  or  three  supporting  bolts 

93  5—  four  supporting  bolts 

EXAMPLE: 
width  =3  6" 
pitch  =   7.5 


28.5 
distance  =   7.75 

56.25 
935 

1  425 
19  95 
199  5 

281  25 
1687  5 
50625 

220.875 
length  =              3 

52593.75 
2 

93  5=  constant 


=  thickness 
662.02^       105187.^ 

662)105187.  (158  or  159  Ibs.  nearly 
662 

3898 
3310 

5887 
5296 

591 


102 


THE  BOILER. 


Rule  to  find  depth  of  steel  girder  for  top  of  a  combustion  cham- 
ber :  Multiply  pressure  by  centers  of  girder  and  by  length  of  girder 
bolts  and  multiply  this  sum  by  length  of  girder  bolts  minus  pitch  of 
same;  divide  this  product  by  constant  multiplied  by  thickness  of 
girder  and  again  by  square  root  of  number  of  bolts.  The  square 
root  of  quotient  is  depth  of  girder. 

FORMULA : 


PXGXLX  (L— p) 

—  =  depth  of  girder 


LEGEND: 


CxTXx/N 


P  =  pressure  =  160  Ibs. 
G  =  girder  centers  =8  J^. 
L=length  of  girder  =  32" 
C  =  constant  6000  for  steel 
C  =  constant  54000  for  iron 
T  =thickness  of  girder  =  2" 
p  =  pitch  of  bolts  =  9" 
N  =  number  of  bolts  =  9 
d=  depth  of  girder  =  9" 


EXAMPLE: 
160=  pressure 
8 .  5  =  girder  centers 

800 
1280 


1360.0 

32  ^length  of  girder 

27200 
40800 


constant  =  6000 
thickness  of  girder  =     2" 


square  root  of 
no.  of  bolts 


12000 

'.'       3 


43520  0 

23  =  length  of  girder  minus  pitch  of  bolts 

1305600 
870400 


36000) 1000960 . 0000 (27 . 8044 
72000 


280960 
252000 

289600 
288000 


5)27.  8044  (5 . 272  =  5&  nearly 
)25  depth  of  girder 


102)   280 
)   204 


160000 
144000 


1047) 
) 


160000  10542) 
144000      ) 


7644 
7329 

31500 
21084 


16000 


)   10416 


BRACES  AND  REINFORCING.  103 

ENGLISH  BOARD  OF  TRADE  RULES  GOVERNING  GIRDERS. 

LEGEND: 
P  =  pressure. 
W  =  width  of  combustion  chamber 


p  =  pitch  of  bolts 


=  distance  between  girder  centers 
L=  length  of  girder 
d  =  depth  of  girder 
T  =  thickness  of  girder 
C  =  constant  for  number  of  bolts 
Constants  vary  according  to  the  iron  or  steel  used,  the  lower  constant  for 

iron. 
Constant  =6000  =when  only  one  supporting  bolt 

9000  to     9900  =when  two  or  three  supporting  bolts 
10200  to  11220  =when  four  to  five  supporting  bolts 
For  five  bolts  use  same  constant  as  for  four 
For  six  or  seven  bolts  use  constant  10500  for  iron 

11550    "   steel 

FORMULAS: 

Cxd2xT 

—  =  working  pressure 
(W— pitch)  XD  XL 

PX(W— pitch)  XD  XL 

—  =  thickness  of  girder 


Cxd2 
PX  (W— pitch)  XDXL 

CXT 


:  depth  of  girder 


REINFORCEMENT   FOR   HOLES   CUT   IN   BOILER  SHELL. 

All  holes  exceeding  6  inches  in  diameter  cut  in  either  the  flat 
heads  or  circumferential  shell  of  steel  boilers  shall  be  reinforced 
with  wrought  or  cast  steel  rings  to  compensate  for  the  material 
removed.  In  lieu  of  such  a  reinforce  ring,  holes  in  flat  heads  may, 
if  preferred,  be  reinforced  by  flanging  the  metal  about  the  hole 
inward  to  a  depth  of  not  less  than  three-quarters  of  an  inch 
measured  from  the  inner  surface.  Reinforce  rings  on  flat  heads 
must  be  efficiently  riveted  to  the  head,  and  must  have  a  sectional 
area  not  less  than  .8  the  section  of  metal  removed,  the  latter  being 
measured  across  the  shorter  axis  of  the  opening. 

Reinforce  rings  on  the  circumferential  shell  must  be  efficiently 
riveted  to  the  shell,  and  must  have  a  sectional  area  not  less  than 
.7  the  section  of  metal  removed,  the  latter  being  measured  across 
the  hole  in  a  direction  parallel  to  the  length  of  the  boiler. 

Reinforce  rings  should  be  of  thickness  not  less  than  that  of  plate 
to  which  attached. 


104  THE  BOILER. 

Rule  to  find  width  of  ring  to  reinforce  an  opening  in  a  boiler 
shell  such  as  a  man-hole,  when  one  ring  is  used :  Multiply  diameter 
of  opening  longitudinally  by  the  thickness  of  plate  and  divide  the 
product  by  twice  the  thickness  of  reinforcement  ring;  add  the 
diameter  of  rivet  hole  to  quotient.  This  will  be  for  single  riveting 
and  when  double  riveted  add  twice  the  diameter  of  rivet  hole. 

FORMULA: 
OXT 

+  1R  =width  of  ring  for  single  riveted 


2XN 
LEGEND: 

R  =  rivet  diameter  hole  =  .  9375 
O  =  diameter  of  opening  =  11" 
T  = thickness  of  shell  =  %"  =  .  5000 
N  =  thickness  of  ring  =  %"  =  .  6250 

EXAMPLE: 

thickness  of  ring  =  .  6250     11"  =diameter  of  opening 

2      .  5000  =  thickness  of  shell  plate 

twice  thickness  of  ring  = :  JU2500  )  5  .  50000  (4 . 4 

5  0000        . 9375  =  diam.  of  rivet  hole 


50000  5.3375=5^"  nearly 
50000 


When  two  rings  are  used  the  thickness  of  each  must  be  at  least 
that  of  shell  and  have  same  tensile  strength  as  that  of  shell  plate; 
a  single  ring  not  less  than  1J4  the  thickness  of  shell. 

Rule  to  find  number  of  rivets  to  be  used  in  a  reinforcement  ring 
for  reinforcing  an  opening  such  as  a  man-hole  in  boiler  shell :  Multi- 
ply the  net  section  of  the  ring  by  four  times  the  tensile  strength  of 
the  material  and  divide  this  product  by  the  product  of  the  shearing 
strength  of  rivet  multiplied  by  its  area. 

FORMULA: 

NSX(^XTS) 

=  number  of  rivets  required 

SSXA 

LEGEND: 

NS  =net  section  =  1 .  5625 
SS  =  shearing  strength  =38000 
TS  =  tensile  strength  =  60000 
A  =area  of  rivet  =  .  6013 


BRACES  AND  REINFORCING.  105 

EXAMPLE: 

38000  =  shearing  strength  60000  =  tensile  strength 

.  6013  -area  of  rivet  4     times 


114000  240000 

38000 
228000  1 .  5625  =  net  section 

240000  =4  times  tensile  strength 
22849.^000 

625000000 
31250 


22849)375000.0000(16  rivets  %"  diameter  required 
22849 


146510 
137094 

9416 

For  a  double  riveted  ring  multiply  net  section  of  one  ring  by 
eight  times  the  tensile  strength  of  material  and  divide  product  by 
the  sum  obtained  by  multiplying  1.85  times  the  shearing  strength  of 
rivet's  sectional  area  and  the  area  of  rivet. 


CHAPTER  V. 

AMENDMENTS    OF    STEAMBOAT    INSPECTION    RULES 
AND  REGULATIONS. 

Lap  welded  boiler  flues  over  4  inches  up  to  and  including"  30 
inches  in  diameter  shall  be  made  of  wrought  iron  or  mild  steel  made 
by  any  process. 

A  test  piece,  2  inches  in  length,  cut  from  a  tube,  must  stand 
being  flattened  by  hammering  until  the  sides  are  brought  parallel 
with  the  curve  on  the  inside  at  the  ends  not  greater  than  three  times 
the  thickness  of  the  metal  without  showing  cracks  or  flaws,  with 
bend  at  one  side  in  the  weld. 

Each  tube  shall  be  subjected  to  an  internal  hydrostatic  pressure 
of  500  pounds  per  square  inch  without  showing  signs  of  weakness 
or  defects. 

All  steel  tubes  shall  have  ends  properly  annealed  by  the  manu- 
facturer before  shipment.  Tubes  must  stand  drilling,  riveting,  and 
calking,  and  work  necessary  to  install  them  into  the  tube  head  with- 
out showing  any  signs  of  weakness  or  defects. 

No  tube  increased  in  thickness  by  welding  one  tube  inside  of 
another  shall  be  allowed  for  use. 

SEAMLESS  STEEL  BOILER  TUBES. 

MATERIAL. 

The  steel  shall  be  made  by  the  open-hearth  process. 

SURFACE    INSPECTION. 

The  pipe  must  be  free,  inside  and  outside,  from  all  surface 
defects  that  would  materially  weaken  it  or  form  starting  points  of 
corrosion.  The  defects  to  be  especially  avoided  are  snakes,  checks, 
slivers,  laps,  pits,  etc.  Pipe  must  be  smooth  and  straight. 

The  following  tests  shall  be  made  before  shipment  by  the  manu- 
facturer : 

(a)  A  test  piece,  2  inches  in  length,  cut  from  a  tube,  must  stand 
being  flattened  by  hammering  until  the  sides  are  brought  parallel 
with  the  curve  on  the  inside  at  the  ends  not  greater  than  three  times 
the  thickness  of  the  metal  without  showing  cracks  or  flaws. 

106 


GOVERNMENT'S  RULES—FLUES  AND  FURNACES.  107 

(b)  Pulling  tests  must  be  made  from  every  50  pieces  furnished, 
or  fraction  thereof,  and  must  show  the  following  results: 

Tensile  strength,  not  less  than  48,000  pounds  per  square  inch. 

Elongation  in  8-inch  specimen,  not  less  than  12  per  cent. 

The  results  of  the  pulling  tests  must  be  forwarded  by  the  manu- 
facturer to  the  purchaser  of  steam  pipe,  who  will  forward  same  to 
local  inspector. 

Any  pipe  used  for  mud  or  steam  drums  must  have  the  ends  of 
same  properly  annealed  before  the  holes  are  drilled  or  the  heads 
are  riveted  in :  Provided,  That  this  paragraph  shall  apply  only  to 
drums  not  exceeding  15  inches  in  diameter  for  use  on  pipe  and  coil 
boilers. 

When  pipe  is  used  for  steam  lines  where  flanges  are  riveted  on 
and  calked,  the  ends  of  the  pipe  shall  be  properly  annealed  before 
drilling  or  riveting  the  flanges  on. 

When  pipes  are  expanded  into  flanges  by  proper  and  approved 
machinery,  and  flared  out  at  the  ends  to  an  angle  not  exceeding  20° 
(said  angle  to  be  taken  in  the  direction  of  the  length  of  the  pipe) 
and  having  a  depth  of  flare  equal  to  at  least  one  and  one-half  times 
the  thickness  of  the  material  in  said  pipe,  such  pipes  may  be  used 
for  all  steam  and  exhaust  pipes  when  tested  to  two  and  one-half 
times  the  working  pressure  and  found  perfect  in  every  respect. 

If  the  pipe  is  used  for  steam  lines  where  the  pipe  is  peened  in 
and 'flanged  over,  the  ends  of  the  pipe  should  be  properly  annealed 
before  the  peening  or  flanging  is  done. 

The  use  of  a  square-nosed  tool  is  recommended  for  cutting  tubes 
and  pipe. 

Provided,  That  this  entire  section  shall  apply  only  to  tubes 
and  pipes  used  or  to  be  used  in  boilers  built  after  June  30,  1905,  and 
to  all  other  pipes  referred  to  in  this  section  subject  to  pressure  in- 
stalled for  use  on  steam  vessels  after  that  date. 

TABLES  AND  EXAMPLES. 

Flues  and  furnaces  safe  working  pressures. 

The  following  table  shows  diameters,  thickness  of  plate  and  safe 
working  pressure  on  flues  in  sections  of  3  feet,  maximum  length 
allowed  5  feet  ,also  sections  of  30"  in  length,  maximum  40". 


108 


THE  BOILER. 


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GOVERNMENT'S  RULES— FLUES  AND  FURNACES.  109 

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110  THE  BOILER. 

Rule  to  find  steam  pressure  allowed  on  any  flue  in  table :  Multi- 
ply crushing  strain  8,000  pounds  (constant)  by  thickness  noted  in 
column  and  divide  the  product  by  diameter  of  flue. 

FIRST  EXAMPLE:  FORMULA: 


CXT 

—  =  working  pressure  allowed 
D 


LEGEND: 


D  =  diameter  of  flue  =15"  EXAMPLE: 

T  =thickness  of  plate  =  M  =  •  25" 

C  =  constant  =  crushing  strain  =  8000  8000  =  constant 

.  25  =  thickness  of  plate 

40000 
16000 

flue  diameter  =  15)  2000.00(133^  Ibs.  working  pressure 

50 

45 

50 

45 


SECOND  EXAMPLE: 

LEGEND: 

T  = thickness  of  plate  =  %  =  .  375 

D  =  diameter  of  furnace  =36" 

C  =  constant  =  8000  =  crushing  strain  EXAMPLE  : 

8000=  constant 

.375  =  3^=  thickness  of  plate 

40000 
56000 
24000 


diameter  =36") 3000000 (83. 3  =lbs.  working  pressure 
288 

120 
108 

120 
108 

12 


GOVERNMENT'S  RULES— FLUES  AND  FURNACES.  Ill 

FLUES. 

The  preceding  table  includes  all  such  riveted  and  lap-welded 
flues,  exceeding-  6  inches  in  diameter  and  not  exceeding  40  inches 
in  diameter,  not  otherwise  provided  for  by  law. 

For  any  such  flue  requiring  more  pressure  than  is  given  in  table, 
the  same  will  be  determined  by  proportion  of  thickness  to  any  given 
pressure  in  table  to  thickness  for  pressure  required,  as  per  example : 

A  flue  not  over  19  inches  in  diameter  and  3  feet  long  requires 
a  thickness  of  .39  of  an  inch  for  176  pounds  pressure ;  what  thickness 
would  be  required  for  250  pounds  pressure? 

FORMULA: 

Pressure  required  X  T 

—  =  thickness  of  plate  required 
P 

LEGEND: 

P  =  pressure  =  176  Ibs. 

T  =  thickness  of  plate  =  .  39  or  %  nearly 

EXAMPLE  : 

250  =increased  pressure  required 
.  39  = thickness  of  plate 

2250 
750 


first  pressure  =  176) 97.  5000 (.5539  =  &   nearly  =  thickness  of 
88  0  plate  required 

9  50 
8  80 

700 
528 


1720 
1580 

136 


Or,  if  .39  inch  thickness  gives  a  pressure  of  176  pounds,  what 
will  .554  inch  thickness  give? 

FORMULA: 

Thickness  of  plate  required  X  P 

—  =pressure 


112  THE  BOILER. 


EXAMPLE: 


.554  =  thickness  of  plate 
176  =  first  pressure 

3324 
3878 
554 


original  thickness  of  plate  =  .39)97.504(250  =lbs.  pressure 

78 

195 
195 


And  all  such  flues  shall  be  made  in  sections,  according  to  their 
respective  diameters,  not  to  exceed  the  lengths  prescribed  in  the 
table,  and  such  sections  shall  be  properly  fitted  one  into  the  other 
and  substantially  riveted,  and  the  thickness  of  material  required  for 
any  such  flue  of  a  given  diameter  shall  in  no  case  be  less  than  the 
least  thickness  prescribed  in  the  table  for  any  such  given  diameter; 
and  all  such  flues  may  be  allowed  the  prescribed  working  steam 
pressure  if,  in  the  opinion  of  the  inspectors,  it  is  deemed  safe  to 
make  such  allowance.  Inspectors  are  therefore  required,  from 
actual  measurement  of  each  flue,  to  make  such  reduction  from  the 
prescribed  working  steam  pressure  for  any  material  deviation  in  the 
uniformity  of  the  thickness  of  material,  or  for  any  material  deviation 
in  the  form  of  the  flue  from  that  of  a  true  circle,  as  in  their  judg- 
ment the  safety  of  navigation  may  require. 


FURNACES. 

The  tensile  strength  of  steel  used  in  constructing  furnaces  shall 
not  exceed  67,000,  and  be  not  less  than  58,000  pounds.  The  mini- 
mum elongation  in  8  inches  shall  be  20  per  cent. 

All  corrugated  furnaces  having  plain  parts  at  the  ends  not  ex- 
ceeding 9  inches  in  length  (except  flues  especially  provided  for), 
when  new,  and  made  to  practically  true  circles,  shall  be  allowed  a 
steam  pressure  in  accordance  with  the  following  formula : 

CXT 

=  pressure 

D 


GOVERNMENT'S  RULES— FLUES  AND  FURNACES.  113 

»- 

Rule  to  find  collapsing  pressure  of  a  spirally  corrugated  furnace, 
corrugations  \l/2"  deep:  Multiply  square  of  thickness  of  flue  in 
thirty-seconds  of  an  inch  by  the  constant  1200  and  divide  by  external 
diameter  of  flue  in  inches  multiplied  by  square  root  of  length  in 
inches. 

FORMULA: 

LEGEND:  T2xl200 

L  =  length  =81"  —  =  collapsing  pressure 

D=  diameter  =  40"  Dx\/L 

T  =  thickness  =  %  =20/32 
C  =  constant  =  1200 

9)81"  (9=sq.  root  EXAMPLE: 

81  of  length  20  =  thickness  in  32nds  of  an  inch 

20 

400  =  thickness  squared 
1200=  constant 


40"  diameter  80000 

9  square  root  of  length  400 


360  360)480000(1333  Ibs.  collapsing  pressure 

360 

1200 
1080 


1200 
1080 

1200 
1080 

120 
MORISON    CORRUGATED    TYPE. 

[In  calculating  the  mean  diameter  of  the  Morison  furnace,  the 
least  inside  diameter  plus  2  inches  may  be  taken  as  the  mean  diam- 
eter, thus — 

(Mean  diameter  =  least  inside  diameter  +  2  inches. ) 

Rule  to  find  safe  working  pressure  on  a  Morison  corrugated 
furnace:  Multiply  constant  15,600  by  thickness  of  plate  and  divide 
by  diameter. 

T  =  thickness  in  inches,  not  less  than  five-sixteenths  of  an  inch. 

C=  15600,  a  constant,  determined  from  an  actual  destructive  test 
under  the  supervision  of  the  Board  of  Supervising  Inspectors, 
when  corrugations  are  not  more  than  8  inches  from  center  to 
center,  and  the  radius  of  the  outer  corrugations  is  not  more 
than  one-half  of  the  suspension  curve. 


114  THE  BOILER. 

FORMULA: 

CXT 

—  =  working  pressure 
D 


LEGEND: 

EXAMPLE: 
D=  diameter  =  42" 

T  =  thickness  of  plate  =  %  =  .$        15600=  constant 
C  =  constant  =  15600  .  5  =  thickness  of  plate 


diameter  =  42" )  7800 .0(185  Ibs.  working  pressure 
42 

360 
336 

240 
210 

30 


COLLAPSING. 

Rules  for  determining  the  collapsing  pressures  on  furnace  flues 
are  given  by  eminent  authorities,  and  these  after  many  tests  and 
experiments.  These  rules  vary  in  method  of  computing  and  in  the 
results;  however,  there  is  a  reasonable  margin  for  safety  in  the 
maximum  results. 

Mutton's  rule  for  rinding  collapsing  pressure : 

Multiply  the  constant  806,300  by  thickness  of  plate  squared  in 
inches  and  divide  product  by  length  of  furnace  in  feet  multiplied  by 
diameter  in  inches. 

FORMULA: 
CXT2 


LxD 


:  collapsing  pressure 


LEGEND: 


C  =  constant  =806300 

T  =  thickness  of  plate  =  ^  =  .  3750 

D  =  diameter  =  3  8" 

L  =  length  of  furnace  =  14  feet 


GOVERNMENT'S  RULES— FLUES  AND  FURNACES.  115 

EXAMPLE: 

806300 -constant 
.  14062500  -thickness  squared 

length       =    14  403150000 

diameter-   38  1612600 

4837800 

152     3225200 

38       806300 


532)  113385. ^7^0000(213  Ibs  -collapsing  pressure 
1064 

698 
532 


1665 
1596 

69 


Nystronvs  rule  for  finding  collapsing  pressure : 

FORMULA : 

C=  constant -200000  T2XC 

Other  data  same  — —collapsing  pressure 

D  X\/L 

EXAMPLE: 

.  14062500  -thickness  squared 
200000  —constant 


142. 12)28125.00000000(197  Ibs.  -collapsing  pressure 

14212 

diameter  —        38 

sq.  rt.  of  length  =   3 .  74  139130 

127908 
1   52 

26  6        112220 
114          99484 

142.12        12736 

Rule  by  Michael  Longridge  for  finding  collapsing  pressure: 
Multiply  constant  174,000  by  thickness  of  plate  squared  in  inches; 
divide  product  by  diameter  multiplied  by  the  square  root  of  length. 

FORMULA: 
T2XC 

=  collapsing  pressure 


Dx\/L 
C=  constant  =  174000 
other  data  same 


1-16  THE  BOILER. 


EXAMPLE: 

length  38      .  14062500  =thickness  squared 

sq.  rt.of  diam.  =     3.74  174000  =  constant 

1  52       56250000000 
26  6       98437500 
114         14062500 


142. 12)24468.7500000(172  Ibs.  =  collapsing  pressure 
14212 


102567 
99484 

30835 
28424 


2411 


LEEDS    SUSPENSION    BULB    FURNACE. 

Rule  to  find  safe  working  pressure  on  a  Leeds  suspension  bulb 
furnace :  Multiply  constant  17,300  by  thickness  of  plate  and  divide 
by  diameter. 

T  =thickness  in  inches,  not  less  than  five-sixteenths  of  an  inch. 

C  =a  constant,  17300,  determined  from  an  actual  destructive  test 
under  the  supervision  of  the  Board,  when  corrugations  are 
not  more  than  8  inches  from  center  to  center,  and  not  less  than 
2  34  inches  deep. 

FORMULA: 

CXT 

=  working  pressure 

D 

LEGEND:  EXAMPLE: 

C  =  constant  =  17300  17300  =  constant 

T  =  thickness  =  %  =  .  375  .375=  thickness  of  plate 

D  =  diameter  =  3  6" 

86500 

121100 

51900 


diameter  36")  6487 . 000  (180  Ibs.  working  pressure 
36 

288 
288 

07 


GOVERNMENT'S  RULES— FLUES  AND  FURNACES.  117 

FOX    TYPE. 

Rule  to  find  safe  working  pressure  on  the  above  type  of  furnace : 
Multiply  constant  14,000  by  thickness  of  plate  and  divide  by  diam- 
eter. 

T  =  thickness  in  inches,  not  less  than  five-sixteenths. 
C  =  14000,  a  constant,  when    corrugations  are  not  more  than   8 
inches  from  center  to  center  and  not  less  than  1  ^  inches  deep. 

FORMULA: 

CxT 

—  =safe  working  pressure 
D 
LEGEND: 

D=  diameter  =  40" 

T  =  thickness  of  plate  =  Y2"  =  .  5 

C  =  constant  =  14000  EXAMPLE: 

14000=  constant 

.  5  =  thickness  of  plate 


Diameter  =40")  7000 . 0  (175  Ibs.  working  pressure 
40 

300 
280 

200 
200 


PURVES  TYPE. 
FORMULA : 

CXT 

—  =  pressure 
D 

T  =thickness  in  inches  not  less  than  seven-sixteenths. 
D  =  least  outside  diameter  in  inches. 

C=  14000,  a  constant,  when  rib  projections  are    not  more  than  9 
inches  from  center  to  center  and  not  less  than  1 3/g  inches  deep. 

BROWN  TYPE. 

CXT 

—  =  pressure 
D 

T  =  thickness  in  inches,  not  less  than  five-sixteenths 

D  =least  outside  diameter  in  inches. 

C=  14000,  a  constant  (ascertained  by  an  actual  destructive  test 
under  the  supervision  of  the  Board  of  Supervising  Inspec- 
tors), when  corrugations  are  not  more  than  9  inches  from 
center  to  center  and  not  less  than  1  finches  deep. 


118  THE  BOILER. 

The  thickness  of  corrugated  and  ribbed  furnaces  shall  be  ascer- 
tained by  actual  measurement.  The  manufacturer  shall  have  said 
furnace  drilled  for  a  one-fourth  inch  pipe  tap  and  fitted  with  a 
screw  plug  that  can  be  removed  by  the  inspector  when  taking  this 
measurement.  For  the  Brown  and  Purves  furnaces  the  holes  shall 
be  in  the  center  of  the  second  flat ;  for  the  Morison,  Fox,  and  other 
similar  types  in  the  center  of  the  top  corrugation,  at  least  as  far 
in  as  the  fourth  corrugation  from  the  end  of  the  furnace. 

TYPE  HAVING  SECTIONS  18  INCHES  LONG. 

CXT 


= pressure 


T  = thickness  in  inches,  not  less  than  seven-sixteenths. 

D  =mean  diameter  in  inches. 

C=  100000,  a  constant,  when  corrugated  by  sections  not  more 
than  18  inches  from  center  to  center  and  not  less  than  2J^ 
inches  deep,  measuring  from  the  least  inside  to  the  greatest 
outside  diameter  of  the  corrugations,  and  having  the  ends 
fitted  one  into  the  other  and  substantially  riveted  together, 
provided  that  the  plain  parts  at  the  ends  do  not  exceed  12 
inches  in  length. 


CONES. 

Rule  to  find  collapsing  pressure  on  a  truncated  cone  up  to  42 
inches  in  length:  Multiply  twice  thickness  of  plate  by  the  tensile 
strength  and  by  the  hypothenuse  length  of  cone ;  divide  this  sum  by 
the  square  inches  in  a  trapezoid  of  equal  dimensions  of  truncated 
cone. 

FORMULA: 

2  X  T  X  TS  X  Hypothenuse 

—  =bursting  pressure 
Area  of  trapezoid 

LEGEND: 

T  =  thickness  of  plate  =  %  =  .  375 
TvS  =  tensile  strength  =60000 
Hypothenuse  =40" 
Area  of  trapezoid  =  1200 


GOVERNMENT'S  RULES— FLUES  AND  FURNACES.  119 

EXAMPLE: 

.  7500  =  twice  thickness  of  %"  plate 
60000=  tensile  strength 

45000.00^0 

40"  =  length  of  hypothenuse  of  cone 


area  of  a  traoezoid  =  1200)  1800000 .0000  (1500  Ibs.  bursting  pressure 
1200 

6000 
6000 


CONE   TOPS. 

Flues  used  in  vertical  boilers  as  upper  combustion  chambers 
formed  in  the  shape  of  a  cone,  when  new  and  made  to  practically 
true  circles,  shall  be  allowed  a  steam  pressure  according  to  the 
following1  formula : 

CxT 

—  =  pressure 
D 

T  =  thickness  of  flue  in  inches,  not  less  than  five-sixteenths. 

D  =outside  diameter  in  inches,  at  the  center  of  the  length  of  the  flue, 

not  to  exceed  42  inches. 
C  =10153,  a  constant,  when  the  length  of  the  flue  does  not   exceed 

42  inches,  measuring  from  center  of  rivet  holes  in  top  of  head 

to  the  center  of  rivet  holes  in  the  tube  head. 

When  the  flue  exceeds  42  inches  in  diameter  at  the  center,  it 
shall  be  deemed  flat  surface  and  must  be  stayed  accordingly. 

Rule  to  find  safe  working  pressure  on  a  truncated  cone  as  in  a 
submerged  tube  upright  boiler,  length  limited  to  40":  Multiply 
constant  8000  by  thickness  of  plate,  minimum  limit  5/16,  and  divide 
by  diameter  (small  and  large  diameter  added  together  and  divided 
by  2). 

LEGEND:  FORMULA: 

C=  constant  =8000  CxT 

T  =  thickness  of  plate  =  ^  =  .  4375  —  =  working  pressure 

D  =  diameter,  small  =3  0"  D 

large   =40" 

EXAMPLE: 

8000=  constant 
large  diam.  40"  . 4375  =  ^  plate 


small  diam.  30" 


2)70  35 

35'  00 


35)3500. 0000(100  Ibs.  pressure 


120  THE  BOILER. 

ADAMSON    TYPE. 

When  plain  horizontal  flues  are  made  in  sections  not  less  than 
18  inches  in  length,  and  not  less  than  five-sixteenths  of  an  inch  thick, 
and  flanged  to  a  depth  of  not  less  than  three  times  the  diameter  of 
rivet  hole  plus  the  radius  at  furnace  wall  (inside  diameter  of  fur- 
nace), the  thickness  of  the  flanges  shall  be  as  near  the  thickness  of 
the  body  of  the  plate  as  practicable. 

The  radii  of  the  flanges  on  the  fire  side  shall  be  not  less  than 
three  times  the  thickness  of  plate. 

The  distance  from  the  edge  of  the  rivet  hole  to  the  edge  of  the 
flange  shall  be  not  less  than  the  diameter  of  the  rivet  hole,  and  the 
diameter  of  the  rivets  before  driven  shall  be  at  least  one-fourth 
inch  larger  than  the  thickness  of  the  plate. 

The  depth  of  the  ring  between  the  flanges  shall  be  not  less  than 
three  times  the  diameter  of  the  rivet  holes,  and  the  ring  shall  be 
substantially  riveted  to  the  flanges.  The  fire  edge  of  the  ring  shall 
terminate  at  or  about  the  point  of  tangency  to  the  curve  of  the  flange, 
and  the  thickness  of  the  ring  shall  be  not  less  than  one-half  inch. 


PLAIN  CIRCULAR  FURNACES  OR  FLUES,  AND  ADAMSON  FURNACES  MADE 
IN  SECTIONS  NOT  LESS  THAN  18  INCHES  IN  LENGTH. 

Rule  to  find  safe  working  pressure  of  an  Adamson  furnace: 
Multiply  length  of  section  by  thickness  of  plate  in  sixteenths;  from 
this,  product  subtract  the  length  of  furnace  multiplied  by  constant 
1.03;  multiply  result  by  constant  51.5  divided  by  the  diameter. 

FORMULA: 

51.5 

[SxT  —  (Lxl-03)]X  --  =  pressure 
:"";  -  i-  '•  D 

LEGEND: 


S  =  length  of  section  = 
D  =outside  diameter  of  furnace  in  inches  =  44" 
L  =  length  of  furnace  in  inches  =  48" 
T  =  thickness  of  plate  in  sixteenths  of  an  inch  = 
C  =  constant  =51.5 
C=  constant  -1.03 


GOVERNMENT'S  RULES— FLUES  AND  FURNACES.  121 

EXAMPLE: 

diameter  =  44) 5 1.5(1. 17  18.75  =  length  of  section 

41  8  =  thickness  of  plate  in  16ths 

75  150.00  48  =  length  of  furnace 

44  49 . 44  1 . 03  =  constant 


3  10  100.56  1  44 

3  08  1.17  48 


7  0392        49.44 
10  056 
100  56 


117 . 6552  =  safe  working  pressure 


VERTICAL   TYPE. 

Cylindrical  flues  used  as  furnaces  in  vertical  boilers,  when  new, 
and  made  to  practically  true  circles,  shall  be  allowed  a  steam  pressure 
by  the  following  formula : 

CxT 

—  =  pressure 
D 

T  =  thickness  of  flue  in  inches,  not  less  than  one-fourth. 

D  =outside  diameter  of  flue  in  inches,  not  to  exceed  42  inches. 

C  =  10,577,  a  constant,  when  the  length  of  the  flue  does  not  exceed 

42  inches,  measuring  from  the  center  of  the  rivet  holes  in  the 

head  to  the  center  of  the  rivet  holes  in  the  leg. 

When  the  flue  exceeds  42  inches  in  diameter,  it  is  deemed  to  be 
flat  surface  and  must  be  stayed  accordingly. 


STEAM    CHIMNEY    FLUES. 

The  Morison,  Fox,  Purves,  or  Brown  types  of  corrugated  fur- 
naces may  be  used  as  flues  for  steam  chimneys  or  superheaters  and 
shall  be  allowed  a  steam  pressure  by  their  respective  formulas,  and 
other  flues,  as  described  below,  when  new  and  made  to  practically 
true  circles  and  shall  be  allowed  a  steam  pressure  by  the  following 
formula : 

CxT 

—  =  pressure 
D 


THE  BOILER. 


T  =  thickness  of  material  in  inches. 
D  =outside  diameter  of  flue  in  inches. 

C  =  12000  for  flues  under  30  inches  in  diameter,  plates  at  least 
five-sixteenths  of  an  inch  thick,  supported  by  angle  rings  at 
least  23^  by  2^  inches. 

C  =  L2000  for  flues  30  inches  and  under  45  inches   in   diameter, 
plates^  at  least  three-eighths  of  an  inch  thick,  supported  by 
„  angle  rings  at  least  2  ^  by  2 }/%  inches. 

•        C=  12000  for  flues  45"inehes  and  under  55  inches   in    diameter, 
^       plates  at  least  seven^ixteenths  of  an  inch  thick,  supported 

by  angle  rings  at  least  3  by  3  inches. 

C  =  12000  for  flues  55  inches  and  under  65  inches  in  diameter, 
plates  at  least  one-half  inch  thick,  supported  by  angle  rings  at 
least  3  by  3  inches. 

C  =  12000  for  flues  65  inches  and  under  75  inches  in  diameter,  plates 
least  nine-sixteenths  of  an  inch  thick,  supported  by  angle 
rings  at  least  3^  by  3^  inches. 

C  =  12000  for  flues   75  inches  and  under  85  inches   in    diameter,  ^ 
plates  at  least  five-eighths  of  an  inch  thick,  supported  by  angle 
rings  at  least  3^j  by  3  finches. 

C  =  12000  for  flues  85  inahes  in  diameter,  plates  at  least  eleven- 
sixteenths  of  an  inch  thick,  supported  by  angle  rings  at  least 
4  by  4  inches. 

For  flues  over  85  inches  in  diameter,  add  one-sixteenth  of  an 
inch  to  eleven-sixteenths  of  an  inch  for  every  10  inches  increase  in 
the  diameter  of  the  flue. 

The  distance,  center  to  center,  between  angle  rings,  or  center  of 
angle  rings  to  center  of  rivets  in  the  heads,  shall  in  no  case  exceed 
2y2  feet. 

The  angle  rings  shall  be  accurately  fitted  and  substantially  riveted 
to  the  flue  and  connected  to  the  outer  shell  by  braces,  which  braces 
shall  not  exceed  20  inches  from  center  to  center  on  the  flue. 


ADAMSON    RINGS. 

Adamson  rings  may  be  substituted  for  the  angle  rings,  but  each 
ring  shall  not  be  at  a  greater  distance  than  2l/2  feet  from  center  to 
center  of  rings,  which  rings  shall  not  be  required  to  be  braced  to 
the  outer  shell. 

Rule  to  find  the  working  pressure  of  an  Adamson  flue  used  in  a 
steam  chimney:  Multiply  constant  by  thickness  of  plate  in  inches 
and  divide  by  diameter. 

LEGEND:  FORMULA: 

T  =  thickness  of  plate  =  ^  =  .  5  C  X  T 

D  =  diameter  =  45"  —  =  working  pressure 

C=  constant  =12000  D 


GOVERNMENT'S  RULES— FLUES  AND  FURNACES.  123 

EXAMPLE: 

12000  =  constant 

.  5  =  thickness  of  plate 

diameter  =  45 )  60000  (133  Ibs.  pressure 
45 

150  •     * 

135          .     -  • 

» 

150       •  • 

135 

15 


Rule  by  Hutton  to  find  collapsing-  pressure  of  ribbed  furnace 
with  ribs  9  inches  centers  and  not  less  Jthan  15/16  deep:  Multiply 
thickness  of  straight  or  plain  part  of  furnace  flue  in  squared  thirty- 
seconds  by  constant  1350  and  divide  by  external  diameter  multiplied 
by  square  root  of  length. 

FORMULA: 
T2X1350 


—  =collapsing  pressure 


LEGEND: 

D=  diameter  =  30" 

L=length=81" 

T  =  thickness  of  plate  =  13/32 


EXAMPLE: 


169    =  13/32  squared 
13  50=  constant 


8450 

diameter  =  30"     507 
square  root  of  length  =9      169 


270)228150(845  Ibs.  collapsing  pressure 
2160 

1215 
1080 


1350 
1350 


124  THE  BOILER. 

Rule  to  get  compressive  strain  on  a  furnace  flue  from  a  collapsing 
pressure :  Multiply  diameter  of  flue  by  pressure  and  divide  product 
by  twice  the  thickness  of  flue  plate. 

FORMULA : 

DXP 

—  =  compressive  strain 
2  XT 

LEGEND: 

D  =  diameter  =30" 

P  =  collapsing  pressure  =  845 

T  =  thickness  of  flue  plate  =  13/32  =  .  40625 

EXAMPLE: 

30"=  diameter 
845  Ibs.  =  collapsing  pressure 

150 

thickness  =  .  40625     120 
2  240 


twice  thickness  =  .81250) 25350.  0000  (3 120  Ibs.  compressive  strain 
243750 


97500 
81250 

162500 
162500 


PLAIN  FLUES. 

Rule  to  find  the  working  pressure  of  a  plain  flue  used  in  a  steam 
chimney:  Multiply  constant  by  thickness  in  inches  and  divide  by 
diameter. 

FORMULA: 

CXT 

—  =  pressure 
D 

LEGEND: 

L  =  length  of  chimney  =8  ft. 

T  =  thickness  of  material  in  inches  =  ^ . 

D  =  outside  diameter  of  flue  in  inches  =  46". 

C  =8000  for  flues  under  32  inches  in  diameter,  plates  at  least  five- 
eighths  of  an  inch  thick,  and  not  exceeding  8  feet  in  length. 

C  =8000  for  flues  over  32  inches  and  under  46  inches  in  diameter, 
plates  at  least  eleven-sixteenths  of  an  inch  thick,  and  not 
exceeding  8  feet  in  length. 


GOVERNMENT'S  RULES— FLUES  AND  FURNACES.  125 

SOCKET    BOLTS. 

For  all  boilers  carrying  a  steam  pressure  of  60  pounds  and  under 
per  square  inch  the  flue  may  be  braced  with  socket  bolts  in  lieu  of 
angle  rings,  such  bolts  to  have  heads  and  the  ends  to  be  threaded 
for  nuts,  with  plate  washers  not  over  12  inches  between  centers  (or 
equivalent)  on  the  inside  of  the  flue;  bolts  to  be  at  least  1  inch  in 
diameter  at  bottom  of  thread. 

For  all  boilers  carrying  a  steam  pressure  of  over  60  pounds  and 
not  over  120  pounds  per  square  inch  the  flue  may  be  braced  with 
socket  bolts  in  lieu  of  angle  rings,  such  bolts  to  have  heads  and  the 
ends  to  be  threaded  for  nuts,  with  plate  washers  not  over  10  inches 
between  centers  (or  equivalent)  on  the  inside  of  flue;  bolts  to  be 
at  least  1^  inches  in  diameter  at  bottom  of  thread. 

Plain  flues,  Adamson  flues,  and  flues  supported  by  angle  bars, 
when  used  as  furnaces,  shall  in  no  case  be  allowed  a  greater  work- 
ing pressure  than  found  by  the  above  formulas. 

LIMITED  FORMULA: 
CXT 


D 


= pressure 


LEGEND: 


C  =  constant  =9900 

T  =  thickness  of  plate  =  ^  =  .  5 

D=  diameter  =  40" 


EXAMPLE: 


9900=  constant 

.  5  =  thickness  of  plate 


diameter  =  40")49500  (123%  Ibs.  pressure 
40 

95 
80 

150 
120 

30 


126 


THE  BOILER. 


Mutton's  rule  to  find  collapsing  pressure  on  a  furnace  flue  lap 
riveted  or  flange  connected :  Multiply  thickness  of  plate  squared 
32nds  by  constant  660  and  divide  by  diameter  multiplied  by  square 
root  of  length. 


LEGEND: 

T  =  thickness  =  ^  =  .  if 
C=  constant  =660 
D=  diameter  =  3  6" 
L=length=64" 


FORMULA: 
T2XC 

DX\/L 


Collapsing  pressure 


EXAMPLE: 

.  144    =  thickness  squared  in  32nds 
660  =  constant 


diameter  =   36     8640 
sq.  root  of  length    =      8  864 


288)95040 (330  Ibs. 
864 

864 
864 


=  collapsing  pressure 


TABLE  OF  COLLAPSING  PRESSURES  OF  FURNACES  BY  W.  S.  HUTTON. 


Diameter  in 
inches 

Length  in 
inches 

Thickness  in 
32nd 

Collapsing  pressures, 
square  inch 

Ibs.  per 

33.5 

360 

11 

113 

42 

420 

12 

100 

42 

300 

12 

119 

54 

36 

8 

120 

38 

86 

16 

436 

36 

24 

8 

218 

36 

24 

12 

490 

36 

48 

12 

350 

43 

23 

17 

842 

CHAPTER  VI. 

SINGLE    RIVETED    LAP   JOINT. 


Causes  for  failure  at  joint : 

First — Shearing  of  one  rivet. 

Second — Tearing  of  plate  between  rivets. 

Third — Crushing  of  rivet  or  plate. 

In  calculating  seams  it  will  be  necessary  to  have  some  data,  and 
to  follow  this  out  we  will  assume  it  to  be  as  follows: 

LEGEND: 

TS  = tensile  strength  =60000 

CS  =  resistance  to  crushing  =95000 

SS  =  resistance  to  shearing  of  rivet  =38000 

D  =  diameter  of  boiler  =48" 

d=  diameter  of  rivet  hole  =13/16  =  .8125 

A  =area  of  rivet  hole  =  .  5185 

T  =  thickness  of  plate  =  5/16  =  .  3125 

P=pitch  =  lJ/8  =  1.8750 

F  =  factor  of  safety  =  5 

First : — resistance  to  shear  one  rivet 

FORMULA: 

A  X  SS  =  resistance  to  shearing  of  one  rivet. 
EXAMPLE: 

.  5185  =area  of  rivet 

38000  =shearing    strength    of    rivet, 

single  shear 
41480000 
15555 


19,703  Ibs.  shearing  strength  of  one  rivet. 
127 


128  THE  BOILER. 

Second : — tearing  the  plate  between  rivets. 

Rule  to  find  strength  of  net  section  of  plate:     From  pitch  of 

rivet,   subtract   diameter   of  rivet   hole   and   multiply   this  sum   by 

thickness  of  plate.     Multiply  this  product  by  the  tensile  strength 
of  plate. 

FORMULA: 
(P— d)  XT  XTS=  strength  of  net  section  of  plate. 

EXAMPLE: 

1.8750=pitch 
.  8125  =  diameter  of  rivet 


1.0625 
.  3125  =thickness  of  plate 

53125 
21250 
10625 
31875 


33203125 

60000  =  tensile  strength 


19,921  =  strength  of  net  section  of  plate. 

Third: — resistance  to  crushing  of  rivet  or  plate. 

FORMULA: 
P  X  T  X  TS  =  strength  of  solid  plate. 

EXAMPLE: 

1 .  8750  = pitch  of  rivets 
.3125  =  thickness  of  plate 

93750 
37500 
18750 
56250 


.58593750 

60000  -tensile  strength 


35156. 

35,156  Ibs.  strength  solid  plate 


LAP  JOINTS.  129 

The  net  section  of  rivets  is  the  weakest  part  of  joint.  To  find 
the  efficiency  of  joint,  multiply  the  weakest  section  by  constant 
100  and  divide  by  the  strength  of  solid  plate. 

EXAMPLE: 

19,703  =shearing   resistance  of  one  rivet 
35,156  *=  strength  of  solid  plate 

35, 156)  19, 703. 00  (.56  =56%  efficiency  of  joint 
17  579  0 


2  125   00 
2  109  36 


Rule  to  find  safe  working  pressure  from  these  calculations :  Mul- 
tiply the  tensile  strength  of  plate  by  the  efficiency  of  joint  and  this 
sum  by  twice  the  thickness  of  plate ;  divide  this  product  by  diame- 
ter of  boiler  multiplied  by  factor  of  safety. 

FORMULA: 
TSX%X(2XT) 


DxF 


=  safe  working  pressure 


EXAMPLE  : 

60000  =  tensile  strength 
.56=%  efficiency 

3600  00 
30000  0 

33600.00 

.6250  =  twice  thickness  of  plate 


168000000 

diam.  of  boiler  =  48"     6720000 
factor  of  safety  =     5  20160000 


240)21000 .  Op^0  (87.5  Ibs.  =  working  pressure 
1920 

1800 
1680 

1200 
1200 


130  THE  BOILER. 

Rule  to  find  thickness  of  plate:  Multiply  pressure  by  factor  6 
and  multiply  again  by  radius  or  one-half  diameter  of  boiler  and 
divide  product  by  tensile  strength  of  plate ;  the  quotient  will  be 
thickness  of  plate. 

LEGEND: 
F=factor  =  6 

R  =  radius  =  30"  or  one-half  diameter. 
TS  =  tensile  strength  =  60000 
P  =  pressure  =125  Ibs. 

FORMULA: 

PxFxR 

—  =  thickness  of  plate 
TS 

EXAMPLE: 

125    =lbs.  pressure 
6    =  factor 

750 

30  =  radius 

tensile  strength  =  60000) 22500000  (3750  =  ^  plate 
180000 


450000 
420000 

300000 
300000 


Rule  to  find  pitch  of  rivets  for  single,  double  and  triple  riveted 
lap  joints  when  the  shearing  strength  of  rivets  is  near  equal  to 
strength  of  net  section  of  plate :  Multiply  area  of  rivet  hole  by 
the  shearing  resistance  of  rivets  and  by  number  of  rows  of  rivets; 
divide  product  by  thickness  of  plate  multiplied  by  tensile  strength; 
add  to  quotient  the  diameter  of  rivet  hole. 

FORMULA : 

AXSSXN 

-  +  DH  =  pitch  single  riveted  joint 
TXTS 

LEGEND: 

A  =area  of  rivet  =  15/16  =  .  6903 
SS  =  shearing  strength  of  rivet  =38000 
N  =  number  of  rows  of  rivets  =  1 
T  =  thickness  of  plate  =  .  4375 
TS  =  tensile  strength  =60000 
DH  =  diameter  of  rivet  hole  = . 9375 


LAP  JOINTS.  131 


EXAMPLE: 

.6903        =  area  of  rivet 

38000  =  shearing  strength 


plate  thickness  =  .  4375  55224000 

tensile  strength  =          60000  20709 


26250 .0000)26231  -  4000  ( .  9992 

23625   0          .  9375  =  diameter  of  rivet  hole 


2606  40  1.9367  =  115/16 -pitch 

2362  50 


243  900 
236  250 

7  6500 
5  2500 


2  4000 

Custom  through  using  iron  rivets  has  established  a  rule  to 
make  the  rivet  hole  1-16  larger  than  the  rivet,  but  owing  to  a 
better  rivet  material  and  use  of  steel  rivets,  experience  has 
proved  that  less  than  1-16  larger  is  better. 

Rule  to  find  diameter  of  a  rivet  for  a  single  riveted  lap  joint  — 
steel  rivets  and  plate:     Add  to  plate  thickness  7-16  of  an  inch. 

FORMULA: 

T  plus  -fe  =  diameter  of  rivet  for  sing'e  riveted  lap  joint 
LEGEND:  EXAMPLE: 

T  = thickness  of  plate  =  y%  =  .  3750      .  3750  =thickness  of  plate 

.4375  =  ^ 


^f    rivet    (this  sectional  area 
after  rivet  has  been  driven) 

The  Board  of  Supervising  Inspectors  of  Steam  Vessels,  in  their 
rules  and  regulations  governing  the  construction  of  steam  boilers 
for  marine  purposes,  prescribe  the  following  rules  for  single  and 
double  riveted  lap  joints : 

d  =T+  y%  inch  for  iron  plates  and  iron  rivets,  single  riveted  lap  joints, 
d  =T+  T^  inch  for  iron  plates  and  iron  rivets,  double  riveted  lap  joints, 
d  =T+  ^  inch  for  steel  plates  and  steel  rivets,  single  riveted  lap  joints, 
d  =T+  y%  inch  for  steel  plates  and  steel  rivets,  double  riveted  lap  joints. 

It  has  been  generally  considered  good  practice  to  have  rivet 
section  percentage  of  strength  higher,  this  for  the  benefits  of  caulk- 


132  THE  BOILER. 

ing  and  increasing  rivet  strength  and  to  make  up  for  depreciation 
due  to  heating  and  driving  rivet;  but  one  authority  on  boiler  con- 
struction says  to  have  plate  higher  in  efficiency  to  provide  for  plate 
deteriorating  due  to  pitting  and  corrosion;  however,  in  designing 
seams  these  conditions  can  be  provided  for  when  computing  boiler 
joints. 

Rule  to  find  center  of  rivet  to  edge  of  plate   (lap)  :     Multiply 
diameter  of  rivet  hole  by  1.5  (one  and  a  half)  constant. 

FORMULA: 
dxC=lap 

LEGEND:  FORMULA: 

d  =  diameter  of  rivet  hole  =  %  =  .  750  .750  =  rivet  diameter 

C  =  constant  =  1.5  1.5=  constant 


3750 
750 

1.1250  =  W  lap 


Rule  to  find  percentage  of  rivet  in  a  single  riveted  lap  joint, 
steel  plate  and  steel  rivets:  Multiply  area  of  rivet  by  number  of 
rows  in  one  pitch  and  by  the  constant  100;  divide  this  product 
by  pitch  of  rivet  multiplied  by  thickness  of  plate  in  inches. 

LEGEND:  FORMULA: 

P=  pitch  of  rivets  =lif  =  1.9375  AxNxC 

A  =area  of  rivet  %  hole  =  .  44179  —  =  rivet  percentage 

C  =  constant  =100  P  X  T 

T  = thickness  of  plate  =  %  =  .  375 

N  =  number  of  rows  of  rivets  =  1 

D  =  diameter  of  rivet  hole  =  %  =  .  750 

EXAMPLE: 

pitch  of  rivet  =  1 . 9375 

thickness  of  plate  =      .375   .44179  =area  of  rivet 
-- - — - —  1  =no.  of  rows 


96875 


135625      .44179 

58125  100=constant 


7265625)44. 1790000(. 60  =60%  rivet  percentage 
43  593750 


5852500 


LAP  JOINTS. 


133 


Rule  to  find  percentage  of  plate  in  single  riveted  joint,  steel 
plate  and  steel  rivets,  when  pitch  and  diameter  of  rivet  are  given : 
From  pitch  of  rivet  subtract  sum  of  diameter  of  hole,  multiply  by 
constant  100  and  divide  by  pitch. 

FORMULA: 

P— dXC 

=  percentage  of  plate 

P 

EXAMPLE: 

1.9375=pitch 
.  750    =  rivet  hole  diameter 


1.1875 

100=  constant 


pitch  =  1 .  9375 )  118 .  7500  (61%  =  percentage  of  plate 
116  250 


2  5000 
1  9375 


5625 


LLOYDS    RULES. 

Rule  to  find  working  pressure:  Multiply  constant  by  thickness 
of  plate  and  by  per  cent  of  joint  efficiency ;  divide  this  product  by 
diameter  of  boiler. 

CONSTANTS  USED. 


'For  iron  plate  punched,  lap  joint 

drilled 

"     punched  double  strap 
"     "         "     drilled 


For  Steel  Plate. 

Lap  joints  punched 

drilled 
double  strap 

punched  

double  strap 

drilled 

LEGEND: 

T  =  thickness  of  plate 
D  =  diameter 
%  = joint  efficiency 


Thick- 

Thick- 

Thick- 

ness 

ness 

ness 

rap 

H 

155 
170 
170 
180 

2  165/4 
180 
180 
190 

%  &  over 
170 
190 
190 
200 

Thick- 

Thick- 

Thick- 

Thick- 

ness 

ness 

ness 

ness 

y8& 

under 
200 

215 

230 

%  &  over 
240 

215 


230 


250 


260 


134  THE  BOILER. 


FORMULAS: 
CXTX% 


D 
PXD 

cx% 


'  working  pressure 
=  thickness  of  plate 


MANCHESTER  STEAM  USERS  ASSOCIATION  FORMULAS: 
TX2X%XTS 


;  DXSXIOO 

DXPXSXIOO 
TX%X2 


= working  pressure 
= thickness  of  plate 


APPENDIX. 

The  following  formulas  are  taken  from  those  of  the  British  Board 
of  Trade  and  are  given  for  the  determination  of  the  pitch,  distance 
between  rows  of  rivets,  diagonal  pitch,  maximum  pitch  and  distance 
from  centers  of  rivets  to  edge  of  lap  of  single  and  double  riveted 
lap  joints,  for  both  iron  and  steel  boilers : 

Let  p  =  greatest  pitch  of  rivets  in  inches. 

n  =  number  of  rivets  in  one  pitch, 
pd  =  diagonal  pitch  in  inches, 
d  =  diameter  of  rivets  in  inches. 
T  =  thickness  of  plate  in  inches. 
V  =  distance  between  rows  of  rivets  in  inches. 
E  ^distance  from  edge  of  plate  to  center  of  rivet  in  inches. 

TO  DETERMINE  THE   PITCH. 

Iron  plates  and  rivets: 

d2X-7854Xn 

1- d —pitch 

T 

Example,  first,  for  single-riveted  joint:  Given,  thickness  of 
plate  (T)  ==  Y-2  inch,  diameter  of  rivet  (d)  =  %  inch.  In  this 
case  n=l.  Required  the  pitch. 

(%)2X.  7854X1     7 

1 —  =  2.077  inches  =  pitch 


LAP  JOINTS.  135 

Example  for  double-riveted  joint:     Given,  t  =  J^  inch  and  d  = 
13/16  inch.    In  this  case  n  =  2. 

2X.  7854X2     13 

-H  --  =  2  .  886  inches  =pitch 
^  16 


For  steel  plates  and  steel  rivets  : 

23Xd2X.7854Xn 


28XT 


+  d.=  pitch 


Example  for  single-riveted  joint:     Given,  thickness  of  plate 
inch,  diameter  of  rivet  =  15/16  inch.     In  this  case  n  =  1. 

23X(if)2X. 7854X1     15 

-H =2 . 071  inches  =  pitch 

28X^  16 


Example  for  double-riveted  joint:     Given,  thickness  of  plate  = 
inch,   diameter  of  rivet  =  %   inch,     n  =  2. 

23X(^)2X. 7854X2 

\-%  =2.  85  inches  =  pitch 


FOR  DISTANCE   FROM    CENTER  OF   RIVET   TO   EDGE   OF   LAP. 
3Xd 


=  E  or  lap 


Example:  Given,  diameter  of  rivet  (d)  =  %  inch;  required 
the  distance  from  center  of  rivet  to  edge  of  plate. 

3X% 

•  = 1 . 312  inches  =E,  for  single  or  double  riveted  lap  joint. 

2 

FOR   DISTANCE    BETWEEN    ROWS    OF    RIVETS. 

The  distance  between  lines  of  centers  of  rows  of  rivets  for  dou- 
ble, chain-riveted  joints  (V)  should  not  be  less  than  twice  the 
diameter  of  rivet,  but  it  is  more  desirable  that  V  should  not  be 
less  than  4d+l.  ' 


136  THE  BOILER. 

Example  under  latter  formula  :     Given,  diameter  of  rivet 
inch  ; 


-  =2.  25  inches  =V 


2 
For  ordinary,  double,  zigzag  riveted  joints: 


(p  +  4d) 


10 

Example  :     Given,   pitch  =  2.85   inches,   and   diameter   of   rivet 

=        inch  : 


-  =  1.487  inches  =V 


10 


DIAGONAL     PITCH. 

For  double,  zigzag  riveted  lap  joint.     Iron  and  steel: 

6p  +  4d 


10 

Example :     Given,  pitch  =  2.85  inches,  and  d  =  %  inch ; 

(6X2.85)  +  (4xJ^) 

—  =2.06  inches  =pd 
10 

MAXIMUM    PITCHES    FOR    RIVETED    LAP    JOINTS. 

For  single-riveted  lap  joints: 

Maximum  pitch  =  (1 .  31  XT)  +  1% 

For  double-riveted  lap  joints: 

Maximum  pitch  =  (2 .  62  X  T)  + 1  %  • 

Example :     Given,  a  thickness  of  plate  =  J/£  inch,  required  the 
maximum  pitch  allowable. 


LAP  JOINTS.  137 

For  single-riveted  lap  joint: 

Maximum  pitch  =(1.3lX^)+l;^=2.28  inches 

For  double-riveted  lap  joint: 

'  Maximum  pitch  =  (2 .  62  X  J^)  +  1  ?s  =2 . 935  inches 

To  determine  the  pitch  of  rivets  from  the  above  formulas,  use 
the  diameter  and  area  of  the  rivet  holes.  The  diameter  of  the 
rivets  as  given  in  the  following  tables  is  the  diameter  of  the  driven 
rivet. 

Any  riveted  joint  will  be  allowed  when  it  is  constructed  so  as 
to  give  an  equal  percentage  of  strength  to  that  obtained  by  the 
use  of  the  formula  given. 

Following  are  single  and  double-riveted  lap  joints  tables,  taken 
from  the  handbook  of  Thomas  W.  Traill,  entitled  Boilers,  Marine 
and  Land;  Their  Construction  and  Strength,  may  be  taken  for  use 
in  single  and  double  riveted  joints  as  approximating  the  formulas 
of  the  British  Board  of  Trade  for  such  joints. 


STEEL  PLATES  AND  STEEL  RIVETS. 
SINGLE-RIVETED  LAP  JOINTS. 


THICKNESS 
OF  PLATE 
IN  INCHES 

DIAMETER 
OF  RIVET 
IN  INCHES 

PITCH  IN 
INCHES 

LAP  IN 
INCHES 

EFFICIENCY 

y± 

1A 

1% 

1 

50 

% 

5/8 

1/^8 

I  L/ 

57 

y± 

1% 

1  3^ 

60 

& 

% 

1% 

i  y$ 

50 

TV 

tt        . 

15^ 

!f\ 

54 

P 

m 

1M 

56 

H 

IK 

52 

% 

1  7^ 

53 

% 

j/% 

2^ 

ITS 

55 

T5 

¥ 

1& 

1M 

47 

I 

2K 

1 

51 
53 

J/8 

114 

1  ^ 

48 

% 

15. 

2 

\\£ 

50 

1^. 

1 

2  TTi 

1*2 

51 

i 

f 

2A 

iH 

46 
48 

138 


THE  BOILER. 


COMPUTING  STRENGTH  OF  A  DOUBLE  RIVETED  LAP 

JOINT. 


Causes  for  failure  at  joint. 

1st.    Resistance  to  shearing  two  rivets. 

2nd.  Resistance  to  tearing  of  plate  between  two  rivets. 

3rd.   Resistance  to  crushing  in  front  of  two  rivets. 

Assuming  a  given  boiler  of  dimensions  and  data  as  follows 
LEGEND: 

D  =  diameter  of  boiler  =  54" 

T  = thickness  of  plate  =  %  =  .  3750 

P  =pitch  of  rivets  =  3^=3.  0625 
TS  =  tensile  strength  =  55000 
CS  =  crushing  strength  of  rivets  =  95000 
SS  =shearing  strength  o;£4Jvets  =38000 

A  =area  of  rivet  hole  ~\l -)=  .  69029  or  .  69 

d  =  diameter  of  rivet  hole  =if  =  .  9375 


First.     Resistance  to  shearing  two  rivets. 

Rule  to  find  shearing  strength  of  rivets  in  single  shear:  Multi- 
ply area  of  rivet  hole  by  number  of  rivets  in  single  shear  and  this 
sum  by  shearing  resistance  of  rivet. 

FORMULA: 

A  X  2  X  SS  =  strength  of  two  rivets  in  single  shear 
EXAMPLE: 

.  69  =area  of  rivet  hole 
2  =  number  of  rows 

1.38 

38000  =  shearing  strength  of  rivet  in 

single  shear 
1104000 
414 


52440.00 
52,440  =  strength  of  two  rivets  in  single  shear 


LAP  JOINTS.  139 

Second.     Resistance  to  tearing  of  plate  between  two  rivets. 

Rule  to  find  strength  in  net  section  of  plate :  From  pitch  of  rivet 
subtract  diameter  of  rivet;  multiply  this  sum  by  thickness  of  plate 
multiplied  by  tensile  strength. 

FORMULA: 

(P — d)  X T  X TS  -strength  in  net  section  of  plate 
EXAMPLE: 

3.  0625 -pitch 
.  9375  -diameter  of  rivet  hole 


2.1250 
20625  —thickness  X  tensile  strength  .3750  —thickness  of  plate 

55000  -tensile  strength 
106250 


42500  18750000 

127500  18750 

42500 


20625.0000 


43828.. 
43, 82 8 -strength  of  net  section  of  plate 


Third.     Resistance  to  crushing  of  plate  in  front  of  two  rivets. 

FORMULA: 

d  X2  XT  XCS  —resistance  to  crushing  in  front  of  two  rivets 
EXAMPLE: 

.9375  =  diameter  of  rivet  hole 
2  —two  times 


1.8750 

.  375  —thickness  of  plate 


93750 
131250 
56250 


.7031250 

95000  -crushing  strength 


35156250000 
63281250 


66796. 
66,796  —resistance  to  crushing  in  front  of  two  rivets 

Rule  to  find  strength  of  solid  plate  :     Multiply  pitch  of  rivets  by 
the  thickness  of  plate  and  this  sum  by  tensile  strength. 

FORMULA: 
P  XT  XTS  =  strength  of  solid  plate 


140  THE  BOILER. 


EXAMPLE: 

3. 062  5  =3, A  pitch 

.375  =  thickness  of  pla-te 

153125 
214375 
91875 


1.1484375 

55000  =  tensile  strength 

5742  1875000 
57421  875 


63 , 164  =  strength  of  solid  plate 


Rule  to  find  efficiency  from  weakest  section  of  joint:  Multiply 
sum  of  weakest  section  by  100  and  divide  by  sum  of  strength  of 
solid  plate. 


FORMULA: 
43,828X100 


63,163 


=  efficiency  of  joint 


EXAMPLE: 

43,828  =  strength  of  net  section  of  plate 
100=  constant 


strength  of  solid  plate  =  63,164)4382800(69   per  cent   efficiency  of 

378984  joint 


592960 
568476 

24484 


Rule  to  find  safe  working  pressure  from  these  calculations : 
Multiply  tensile  strength  of  plate  by  joint's  efficiency  and  multiply 
this  sum  by  twice  the  thickness  of  plate  and  divide  this  product  by 
the  diameter  of  boiler  in  inches  multiplied  by  factor  of  safety. 

FORMULA: 
TSX%X(2XT) 


DxF 


= working  pressure 


LAP  JOINTS.  141 

EXAMPLE  : 

55000  =  tensile  strength 
.  69  =  efficiency  of  joint 


495000 
330000 

37950.00 

750  =  twice  thickness  of  plate 


diam  of  boiler  =    54"   1897500 
factor  of  safety  =      5  265650 


270)28462 .  $J0  (105  Ibs.  working  pressure 
270 


1462 
1350 

112 

When  finding  diameter  of  rivet  holes  for  lap  and  butt  joints,  the 
following  constants  are  used: 

C=2.25  for  lap  joints  double  riveted  up  to  and  including  y2" 
plate. 

C=1.9  for  triple  riveted  lap  joint  up  to  J/£"  plate. 

C=1.8  for  butt  joints  triple  and  quadruple  riveted. 

Rule  to  find  diameter  of  rivet  hole :  The  square  root  of  product 
of  thickness  of  plate  in  inches  multiplied  by  constant  used  in  con- 
nection with  joint  form  and  plate  will  give  diameter  of  rivet  hole. 

LEGEND:  FORMULA: 

T  =  thickness  of  plate  =  &  =  .  4375  N/TxC  = diameter  of  rivet  hole 

C=  constant  =2. 2  5 

EXAMPLE: 

.4375  =  thickness  of  plate 
2.25  =  constant 


21875 
8750 
8750 

9) .  984375  (.  9921  =1"  nearly  or  hole  for 
.  81  rivet 

189)  1743 
)  1701 

1982)   4275 

)   3964 
\ 

19841)   31100 

J   19841 

\ 

)   11259 


142  THE  BOILER. 

Rule  to  find  diameter  of  shell :  Multiply  tensile  strength  by 
thickness  of  plate  in  inches  and  by  per  cent  of  joint;  divide  this 
product  by  pressure  multiplied  by  the  factor. 

FORMULA: 
TSxTx%of  joint 


PXF 
LEGEND: 


X  2  =  diameter  of  shell 


P=  pressure  =  130 

T  =  thickness  of  plate  =  %  =  .  5 

%  =  percentage  of  joint  =  80  EXAMPLE  : 

TS  =  tensile  strength  =  60000  60000  tensile  strength 

.  5  =  thickness  of  plate 

pressure  =  130     30000.0 

constant  =      6  80  =  joint  efficiency 

780)  24000. 00(30=  radius 
2340  2 


600         60"  diameter 

Rule  to  find  tensile  strength  of  plate  for  boiler :  Multiply  given 
pressure  per  square  inch  by  tensile  strength;  multiply  this  by  one- 
half  diameter  of  boiler ;  divide  by  the  given  thickness  of  material  in 
inches,  and  the  quotient  will  give  the  required  tensile  strength  per 
square  inch  in  pounds. 

FORMULA: 

(PxT$)X(^of  D) 

—  =  tensile  strength 
T 

LEGEND: 

TS  = tensile  strength  =  60000 
P  =  pressure  =  125  Ibs. 
D  =diameter  of  boiler  =  60" 
T  =  thickness  of  plate  =  .  3750 

EXAMPLE: 

125  =  pressure 

60000  =  tensile  strength 


7500000 

30  =  Y<>,  the  diameter 


thickness  of  plate  =  .  3750)225000000  (60000  Ibs.  =tensile  strength 
22500 


00000 


LAP  JOINTS.  143 

Rule  to  find  thickness  of  shell  plate  when  percentage  of  joint  is 
known :  Multiply  diameter  of  shell  by  pressure  and  again  by  factor 
of  safety  and  multiply  this  sum  by  100 ;  divide  product  by  tensile 
strength  multiplied  by  efficiency  of  seam  multiplied  by  2. 

LEGEND:  FORMULA: 

D=  diameter  =  60"  DxPXFXlOO 

P  =  pressure  =  150  —  =  thickness  of  shell  plate 

F=f  actor  of  safety  =  5  TSX%X2 

%  =  percentage  of  seam  strength  =  80 
TS  =  tensile  strength  =  60000 
C  =  constant  =  100 

EXAMPLE: 

60"  =  diameter  of  shell 
ISO  =  pressure 

3000 
60 

tensile  strength  =  60000   9000 

percentage  =     80     5  =factor 

4800000  45000 
two  times  =      2     100=  constant 


9600000) 4500000  . 0000  ( .  4687  =  15/32"  =  thickness 
3840000  0      required 


660000  00 
576000  00 


84000  000 
76800  000 

7200  0000 
6720  0000 

480  0000 


Rule  to  find  diameter  of  steel  rivet  for  steel  plate  double  riveted 
lap  joint  :    Add  y%  of  an  inch  to  plate  thickness. 

FORMULA: 
^  plus  T  =  diameter  of  rivet 

T  =thickness  of  plate  =  •&  =  .  4375     EXAMPLE  : 

.4375  =  plate 
.375    = 


8125  =       rivet  diameter 


144  THE  BOILER. 

Rule  to  find  pitch  of  rivet  in  a  double  riveted  lap  joint  —  steel 
plate,  steel  rivets :  Multiply  square  of  diameter  of  rivet  hole  by 
constant  23,  this  sum  by  .7854;  then  multiply  this  product  by  the 
number  of  rows  of  rivets;  divide  by  diameter  of  rivet  multiplied 
by  constant  28,  and  add  diameter  of  rivet  hole  to  quotient.  Result 
gives  pitch  of  rivet. 


FORMULA: 
d2X23X.7854xN 

dx28 


+  d  =  pitch 


d  =  diameter  of  rivet  hole  =  %  =  .  9375 

N  =  number  of  rows  =  2  EXAMPLE: 


.9375  =  diameter  rivet  hole 
.9375 


46875 
65625 
28125 
84375 

[squared 


.87890625=  diameter  of    rivet    hole 
23=  constant 

263671875 
175781250 


20 

.7854 

808592 
1010740 

diam.  of  rivet  hole  =    .  9375      1617184 
constant  =  28   1415036 


75000  15,87670392 
19750  2  rows  of  rivets 


26 .  2500)31.75340784  (1 . 2096 

262500  .  9375  =diameterof  rivethole 


550340         2. 1471=  2 &  nearly  =pitch 
525000 


2534078 
2362500 

1715784 
1S75000 

140784 


LAP  JOINTS.  145 

Rule  to  find  distance  between  rows  of  chain  double  riveted  joint: 
To  four  times  the  diameter  of  one  rivet  hole  add  one  and  divide  by 
two. 

FORMULA: 
4d  plus  1 


= distance  between  rows  chain  riveted  joint 


2 

LEGEND: 
d  =  diameter  of  rivet  hole  =  J/g  =  .  8750 

EXAMPLE  : 
.  8750  =  diameter  of  rivet  hole 


3.5000 

1 .  0000  added 


2)4.5000 


2  . 2500  =  2  }£'  distance  between  rows 

Rule  to  find  diagonal  pitch  of  rivet :    To  four  times  the  diameter 
of  rivet  hole  add  six  times  the  pitch  on  straight  line  and  divide  by  10. 

FORMULA: 

4d  +  6P 

—  =  diagonal  pitch 
10 
LEGEND: 

d  =diameter  of  rivet  hole  =  %  =  .  8750 
p=pitch=3^=3.3750 

EXAMPLE: 

3 .  3750  =  pitch  .8750  =  diameter  of  rivet  hole 

6     times  4     times 


20.2500  3.5000=4  times  diameter 

V-  -  20.  2500  =6  times  pitch 

10)23 .  7500  (2 . 3750  =2 %  diagonal  pitch  of 
20  rivets 

37 
30 

75 
70 

50 
50 


146  THE  BOILER. 

Rule  to  find  spacings  center  of  rivet  to  edge  of  plate.     Multiply 
diameter  of  rivet  by  3  and  divide  by  2. 
FORMULA: 

3Xd 

— -  =  distance  from  center  of  rivet  to  edge  of  plate 
2 

d=diam.  of  rivet  %  =  .  8750         EXAMPLE: 

.8750 
3 


2)2.6250 


1.3 125=1^  inch  distance 

Rule  to  find  pitch  of  rivet  to  give  best  percentage  of  strength 
in  a  double  zig  zag  riveted  joint:  Multiply  twice  the  rivet  sectional 
area  by  the  shearing  strength  of  rivet  and  divide  by  thickness  of 
plate  multiplied  by  its  tensile  strength ;  add  to  product  one  diameter 
of  rivet. 

FORMULA: 
(2XA)XSS 

—  plus  1  diam.  of  rivet  =  pitch 
LEGEND:  TxTS 

A  =  rivet  area  =  £!   =.5185 
SS  =  shearing  strength  one  rivet  =38000 
T  =  plate  thickness  =  %  =  .  3750 
TS  =  tensile  strength  of  plate  =  60000 
d  =  diameter  of  rivet  =£f  =.8125          EXAMPLE: 

.5185  =  sectional  area  of  rivet 
2 

1 .  0370  =twice  sectional  area  of  rivet 

38000  =  shearing  strength  of  one  rivet 


Y%  plate  =  .3750  82960000 

tensile  strength  =          6000031110 


22500. 0000)39406. 0000 (1.7513 

22500  .  8125  =diam.  of  one  rivet 


169060  2.  5 638=  2 &  inch  pitch 

157500 


115600 
112500 

31000 
22500 


85000 
67500 

17500 


LAP  JOINTS. 


147 


Rule  to  find  plate  percentage  in  a  double  riveted  lap  joint 
From  pitch  of  rivet  subtract  diameter  of  rivet  and  multiply  by  con- 
stant 100;  divide  this  product  by  pitch  of  rivet. 

LEGEND-  FORMULA: 

P -pitch  =3^ -3. 125  (P— d)XlOO 

—=  percentage  of  plate 


d  =  diameter  of  rivet  hole 
C=  constant  =  100 


=  .8750 

EXAMPLE: 

3 . 1250  =pitch  of  rivet 
.  8750  =diameterof  rivet  hole 


2.2500 

100=  constant 


3 . 1250)225  .  0000  (72  =  percentage  of  plate 
218750 


62500 
62500 


Rule  to  find  percentage  of  rivet  in  a  double  riveted  lap  joint: 
Multiply  area  of  rivet  by  the  number  of  rows  of  rivet  in  one  pitch ; 
multiply  this  product  by  100  and  by  the  constant  23;  divide  this 
product  by  pitch  multiplied  by  thickness  of  plate  and  constant  28. 

FORMULA: 
.4375         AXNX100X23 

=per  cent,  of  rivet 


LEGEND: 

T  =  thickness  of  plate  = 
P  -pitch  =3%  =3. 125 
A  =area  of  rivet  hole  =  %  =  .  6013 
d  =diameter  of  rivet  =  %  =  .  8750 
N  =  number  of  rows  ==  2 

pitch  =3. 125 
thickness  of  plate  =    .4375 


PXTX28 


section 


EXAMPLE: 


6013  =area  of  rivet  hole 
2  rows 


15625 
21875 
9375 
1  2500 

1.3671875 

constant=  28 


1.2026 
100 


=  constant 


120.2600 

23  =  constant 


10  9375000 
27  343750 

38.2812500 


3607800 
2405200 

38 . 281  )2765  .  9800  (72.2=  %  of  rivet  strength 
2679  67 


86  310 
76  562 

9  7480 
7  6562 


2  0918 


148  THE  BOILER. 

Rule  to  find  bursting  pressure  of  boiler:  Multiply  tensile 
strength  by  twice  the  thickness  of  plate  and  divide  by  the  internal 
diameter  of  boiler. 


FORMULA : 
TSX(2XT) 


D 
LEGEND : 


= bursting  pressure 


TS  =  tensile  strength  =60000 
T  =  thickness  of  plate  =  %  =  .  375 
D  =internal  diameter  =  60" 

EXAMPLE: 

thickness  of  plate  =  .375  60000    =  tensile  strength 

2  .  750  = twice  thickness  of  plate 

twice   thickness  =       .750  3000000 

420000 


internal  diameter  =60")  45000. 000  (750  Ibs.  per  square  inch  burst- 
420  ing  pressure 

300 
300 


The  bursting  pressure  divided  by  the  factor  of  safety  will  give  the  safe 
working  pressure.  The  factor  of  safety  of  5  has  been  generally  accepted  by 
eminent  engineers  and  boilermakers. 

factor  =  5) 750  per  sq.  inch  bursting  pressure 
150  Ibs.  working  pressure 


Rule  to  find  working  pressure  on  boilers  from  a  lowest  per- 
centage of  joint:  Multiply  tensile  strength  of  material  by  the  lowest 
percentage  of  joint,  then  by  twice  the  thickness  of  plate  and  divide 
by  diameter  multiplied  by  factor  of  safety. 

FORMULA: 

TSX%X(2XT) 

—  =working  pressure 

DXF 

LEGEND: 

TS  =tensile  strength  =  60000 
%  = lowest  percentage  of  joint  =  80 

T  =  thickness  of  plate  =  %  =  .  500 

D  =internal  diameter  =  71.1250  (outside  =  72" ) 


Internal 


LAP  JOINTS. 

EXAMPLE  : 

60000      =  tensile  strength 
80    =  percentage  of  joint 


149 


diameter  of  boiler  -  71 . 1250  4800000 

factor  of  safety  =  6  1 . 0000  =  twice  thickness  of  plate 

426.  75^0)4800000 . 0000  (112  Ibs.  working  pressure 
4267500 


5325000 
4267500 

10575000 
8535000 

2040000 


Rule  to  find  safe  working  pressure  according  to  the  U.  S.  Gov- 
ernment rule  is  as  follows :  Multiply  one  sixth  of  the  lowest  tensile 
strength  found  stamped  on  any  plate  by  the  thickness  of  same, 
expressed  in  inches  or  decimal  parts  of  same,  and  divide  by  the 
radius  or  half  of  diameter  expressed  in  inches.  The  result  will 
give  pressure  allowed  for  a  single  riveted  boiler;  when  double 
riveted  add  20  per  cent.  This  rule  is  based  on  the  rivet  and  plate 
section  being  equal  and  holes  drilled. 


Thickness 
of  plate 

Diameter 
of  rivet 

Pitch  in 
inches 

Lap  in 
inches 

Distance 
between 
rows 

Efficiency 

M 

H 

^ 

\l 

1 

•iS- 

69 

72 

M 

H 

2  % 

111 

li| 

74 

T§ 

N 

2ft 

IM 

1^ 

68 

ft 

tt 

1% 

70 

.    A 

2K 

i  J^ 

1^| 

72 

|| 

M 

iM 

1  K 

68 

if 

it 
K 

2% 

JS 

2 

69 

71 

* 

^ 

2  & 

i  j4 

65 

ft 

K 

2« 

il 

22 

67 

7 

3  _^. 

70 

\^ 

K 

2tt 

ift 

21" 

65 

y>, 

if 

3 

I'H 

2K 

66 

/^ 

i 

3  1^ 

l^i 

2^ 

68 

ft 

g 

15 

^ 

2 

63 
65 

150 


THE  BOILER. 


COMPUTING  STRENGTH  OF  TRIPLE  RIVETED  LAP 

JOINTS. 


Causes  for  failure  at  joint. 


1st.      Resistance  to  shearing  three  rivets. 

2nd.     Resistance  to  tearing  between  three  rivets. 

3rd.      Resistance  to  crushing  in  front  of  three  rivets. 

Assuming  a  boiler  of  dimensions  and  data  as  follows : 
LEGEND: 

T  -thickness  of  plate  ==  y%  =  .  375 
TS  =  tensile  strength  =  55000 

d  -diameter  of  rivet  = 13/16  =  .  8125 

A  =  area  of  rivet  hole  =13  X16  =  .5185 

P  =pitch  of  rivet  =  3  J4  =  3 .  2500 
SR  =  shearing  resistance  of  rivets  =38000 
CS  =  crushing  strength  of  rivet  and  plate  =  95000 

D  =  diameter  of  boiler  =  60" 

F  =  factor  of  safety  =  5 

First.     Resistance  to  shearing  of  three  rivets. 

Rule  to  find  strength  of  rivets  in  single  shear :  Multiply  area 
of  rivet  hole  by  number  of  rivets,  and  multiply  this  sum  by  the 
shearing  resistance  of  rivet  material. 

FORMULA: 

Ax  No.  of  rivets  XSR  =  strength  of  rivets  in  single  shear 
EXAMPLE: 

.5185  =area  of  rivet  hole 
3  =  number  of  rivets 


1.5555 

38000  =  shearing  resistance  of  rivets 


124440000 
46665 

59109.0000 
59,109  Ibs.  =  strength  of  three  rivets  in  single  .chear 


LAP  JOINTS.  151 

Second.     Resistance  to  tearing  of  plate  between  three  rivets. 

Rule  to  find  strength  of  net  section  of  plate :  From  pitch  of 
rivets  subtract  diameter  of  rivet  hole  and  multiply  by  thickness  of 
plate  and  multiply  this  sum  by  the  tensile  strength  of  plate. 

FORMULA: 

(P — d)  XTxTS=  strength  of  net  section  of  plate 
EXAMPLE  : 

3 . 2500  -pitch  of  rivet 
.  8125  =  diameter  of  rivet  hole 


2.4375 

.375  =  thickness  of  plate 

121875 
170625 
73125 


9140625 

55000  =  tensile  strength 


45703125000 
45703125 

50273.4375000 
50,273  ^strength  of  net  section  of  plate 

Third :     Resistance  to  crushing  in  front  of  plate  in  front  of  three 
rivets. 

FORMULA: 

dX3xTxCS=  resistance  to  crushing  in  front  of  three  rivets 

EXAMPLE: 

.8125  =  diameter  of  rivet 
3  =  three  rivets 


2.4375 

.375  =  thickness  of  plate 


121875 
170625 
73125 

9140625 

95000=  crushing  strength  of  rivet 
and  plate 


4570  3125000 
82265  625 

86835.9375000 

86,835  Ibs.  =  resistance  to  crushing  of  material 


152  THE  BOILER. 

Rule  to  find  strength  of  solid  plate :     Multiply  pitch  of  rivets  by 
thickness  of  plate  and  this  sum  by  tensile  strength  of  material. 


FORMULA: 
P XT XTS  =  strength  of  solid  plate 

EXAMPLE: 


3.  2500 -pitch 

.375  =  thickness  of  solid  plate 

162500 
227500 
97500 


1.2187500 

55000  =  tensile  strength 

6093  7500000 
60937  500000 


67031.2500000 
67,031  Ibs.  -strength  of  solid  plate 


Rule  to  find  efficiency  of  this  joint:     Divide  net  section  of  plate 
by  strength  of  solid  plate. 

EXAMPLE: 

50,273  =net  section  of  plate 
67,031  =  strength  of  solid  plate 

67031) 50273 .  000  ( .  749  =efficiency 
46921   7 


3351  30 
2681  24 


670  060 
603  279 

66  781 


LAP  JOINTS. 


153 


Rule  to  find  safe  working  pressure  from  these  calculations: 
Multiply  tensile  strength  of  plate  by  efficiency  of  joint  and  multiply 
this  sum  by  twice  thickness  of  plate ;  divide  this  product  by  diameter 
of  boiler  in  inches  multiplied  by  factor  of  safety. 


EXAMPLE: 


55000  =  tensile  strength  of  plate 
.  749  =  percentage  of  joint 


495  000 
2200  00 
38500  0 

41195.000 

.  7 500    =  twice  thickness  of  plate 


diam.  of  boiler  =  60"  2059  7500 
factor  of  safety  =    5   28836  5 


300)30896.23^(102.9  Ibs.  working  pressure 
300 


896 
600 

2962 
2700 

262 


Thickness 
of  plate 


Diameter 
of  rivet 


I 
I 

1 


14 

\ 
!ii 


Pitch  in 
in  inches 


Lap  in 
in  inches 


14 


Distance 

between 

rows 


2 


Efficiency 


76 
80 
81 
76 
76 
79 
76 
77 
79 
73 
76 
77 
73 
74 
76 
72 
73 


CHAPTER  VII. 

BUTT  JOINT  DOUBLE  STRAPPED  AND  DOUBLE 
RIVETED. 


Where  butt  straps  are  used  in  the  construction  of  marine  boilers, 
the  straps  for  single  butt  strapping  shall  in  no  case  be  less  than 
the  thickness  of  the  shell  plates;  and  where  double  butt  straps  are 
used,  the  thickness  of  each  shall  in  no  case  be  less  than  five-eighths 
(^s)  the  thickness  of  the  shell  plates. 

A  rule  to  find  thickness  of  butt  straps  is  as  follows :  Multiply 
the  thickness  of  shell  plate  by  factor  5  and  this  sum  by  the  wide  pitch 
of  rivets  in  inches  minus  diameter  of  one  rivet ;  divide  this  product  by 
the  wide  pitch  minus  two  times  diameter  of  rivet  multiplied  by 
constant  8. 

FORMULA: 
TxFx(WP— d) 


WP— (2Xd)xC 


LEGEND: 


=  thickness  of  each  butt  strap 


T  =  thickness  of  plate  =  ^  =  •  4375 
d  =diameter  of  rivet  =  %  =  .  8750 
WP=wide  pitch  =6%  =6.  7500 
F=factor  =  5 
C=  constant  =8 


154 


BUTT  JOINTS.  155 

EXAMPLE: 

.  4375  =  thickness  of  plate 
5  = factor 

2  . 1875  =5  times  thickness 
5.8750  6.  7 5 00=  wide  pitch 

wide  pitch  =    6 .  7500  .  8750  =rivet  diameter 

twice  rivet  diam.  =    1.  7500          1093750 


153125  5.8750 


5.0000     175000 
constant  =  8   109375 


40 .  0W)  12 .  85150JW  ( .  3212  =  thickness  of  butt  strap 
12  0  =  $£  approximately 

85 
80 

51 
40 

115 
80 

35 

When  joints  have  one  strap,  butt  or  lap,  the  rivets  are  in  single 
shear  only.  In  triple  riveted  joints,  double  strap,  the  two  inner  rows 
are  in  double  shear  and  the  outer  in  single  shear. 

Rule  to  find  strength  of  a  solid  strip  of  plate  or  resistance  to  a 
tensile  strength :  Multiply  width  of  strip  by  thickness  of  plate  and 
this  product  by  the  tensile  strength  of  material. 

FORMULA: 

WxTxTS  =  strength  of  solid  plate 
LEGEND: 

W  = width  of  strip  =6.3750 
T  =  thickness  of  plate  =  .4375 
TS  =  tensile  strength  =60000 

EXAMPLE: 

6.3750=width  of  strip 
.4375  =  thickness  of  plate 


318750 
446250 
191250 
2  55000 

2.78906250 

60000  =  tensile  strength 


1 67343. 
167,343  Ibs.  =strength  of  solid  plate 


156  THE  BOILER. 

BUTT  JOINT,  DOUBLE  STRAP  AND  DOUBLE  RIVETED. 

Possible  causes  for  failure. 

First.         Resistance  to  tearing  of  plate  at  outer  row  of  rivets. 

Second.     Resistance  to  shearing  of  two  rivets  in  double  shear  and  one  in 

single  shear. 
Third.        Resistance  to  tearing  of  plate  at  inner  row  of  rivets  and  shearing 

one  of  the  outer  row  single  shear. 

Fourth.     Resistance  to  crushing  in  front  of  three  rivets. 
Fifth.         Crushing  in  front  of  two  rivets  and  shearing  one  rivet. 

LEGEND: 

T  =  thickness  of  plate  =  &  =  .  4375 
dh  =diameter  of  rivet  hole  =  if  =  .  8125 
D  =  diameter  of  boiler  =  60" 


p=pitchof  rivets  =4  ^  =4. 3750 
TS 


AS  =  tensile  strength  =  60000 

A  =area  of  rivet  hole  =  if  -  .  5185 
SS=shearing  strength  of  rivet,  single  shear  =38000 
DS=       "  "       "      double     "     =70300 

N  =  number  of  rows  of  rivets  =2 
CS  =  crushing  strength  of  material  =95000 

F  =  factor  of  safety  =-5 

First.       Resistance  to  tearing  at  outer  row  of  rivets. 

FORMULA: 
(p — dh)  xTxTS  =net  section  of  plate 

EXAMPLE: 

4 . 3750  =pitch  of  rivet 
.  8125  =diameter  of  rivet  hole 


3.5625 

.4375  =  thickness  of  plate 


178125 
249375 
106875 
1  42500 

1.55859375 

60000  =  tensile  strength 


93,515  Ibs.  =  strength  of  net  section  of  plate. 

Second.     The  resistance  to  shearing  two  rivets  in  double  shear  and  one  in 
single  shear. 

FORMULA: 
A  X  N  X  DS  +  ( A  X  SS )  =  total  shearing  strength  of  rivets 


BUTT  JOINTS.  157 


EXAMPLE: 


.5185  =area  of  rivet  hole 

2  =  number  of  rows  of  rivets 

1.0370 

70300  —  shearing  strength 

double  shear 


area  of  rivet  =    .5185  3111000 

single  shearing  strength  =          38000       72590 


4148  0000       72901. J000 
15555  19703  .  -area  multiplied  by  SS 


19703.  JW        92604  lbs.=  total  shearing   strength 

of  rivets 


Third.     The  resistance  to  tearing  at  inner  row  of  rivets  and  shearing  of  one 
rivet. 

FORMULA: 
(p — 2dh)  XTXTS+  (AxSS)  =  resistance  to  tearing  at  inner  row 

EXAMPLE: 

4. 3750 -pitch  of  rivets 

1 .  6250  =two  diameters  of  rivet  hole 


2.7500 
.4375  -thickness  of  plate 


137500 
192500 
82500 
1   10000 


1.20312500 

60000  —tensile  strength 

72187.^0000000 

19703    -area  multiplied  by  SS 


91890  Ibs.  —resistance  to  tearing  at  inner  row 
of  rivets 


Fourth.     The  resistance  to  crushing  in  front  of  three  rivets. 

FORMULA: 
dh  X  3  X  T  X  CS  =  resistance  to  crushing 


158  THE  BOILER. 


EXAMPLE  : 

.  8125  =diameter  of  rivet 
3  =  three  rivets 


2.4375 
.4375  =  thickness  of  plate 


121875 
170625 
73125 
97500 

1.06640625 

9 5 000=  crushing  strength 

5332  03125000 
95976  5625 


101308  .^9^/7^000  Ibs.  =  resistance  to  crushing  strength 
in  front  of  three  rivets 

Fifth.     The  resistance  to  crush  in  front  of  two  rivets  and  shearing  of  one  rivet 

FORMULA: 
2xTxCS+  (AxSS)  =resistance  to  crushing  plate  and  shearing  one  rivet 

EXAMPLE  : 

.4375  = thickness  of  plate 
2  =two  rivets 


.  8750=twice  thickness  of  plate 
95000  =  crushing  strength 

43750000 
78750 


83125.0000 

19703  =area  multiplied  by  SS 


102828  Ibs.  ^resistance   to   crushing  plate   and 
shearing  one  rivet 

Strength  of  solid  plate. 

FORMULA: 
p  xTxTS  =  strength  of  solid  plate 

EXAMPLE: 
4.3750=pitch 
.4375  =thickness  of  plate 

218750 
306250 
131250 
1  75000 


1.91406250 

60000=  tensile  strength 


1 14843.^000000  Ibs.  ^strength  of  solid  plate 


BUTT  JOINTS. 


159 


To  find  efficiency  of  joint  from  these  computations :     Divide  weakest  sec- 
tion of  plate  by  strength  of  solid  plate. 

EXAMPLE: 

Weakest  section  of  plate  =91890 
Strength  of  solid  plate  =114843 

1 14843 )  91890 . 00  ( .  80  ^efficiency  of  joint 
91874  4 


15   60 

Rule  to  find  safe  working  pressure  from  joint  efficiency :  Multi- 
ply tensile  strength  of  plate  by  joint  efficiency  and  multiply  that 
product  by  twice  the  thickness  of  plate ;  divide  by  diameter  of  boiler 
multiplied  by  factor  of  safety. 

FORMULA: 
TSX%X(2XT) 

—  =safe  working  pressure 
DXF 

EXAMPLE  : 

60000  =tensile  strength 
.  80  =  efficiency,  of  joint 


48000.  ( 
.8750 

2400000 

diameter  of  boiler  =  60"  3360000 
factor  =    5    3840000 


300)  42000.  W*0  (140  Ibs.  =  working  pressure 
300 


1200 
1200 


DOUBLE   RIVETED  BUTT  JOINTS. 


s 


gw 

C  51 


Y6  m 

X" 


4%  " 


9      in 
9%  " 


l^in 


2K   " 


83 
82.9 

82 
80 


160  THE  BOILER. 

BUTT  JOINT  DOUBLE  STRAPPED  TRIPLE  RIVETED. 


©"      © 


Rule  to  find  diagonal  pitch  of  rivets  for  a  butt  joint  double  strap 
and  triple  riveted: 

To  the  horizontal  pitch  multiplied  by  6  add  diameter  of  rivet 
multiplied  by  4  and  divide  result  by  10. 

FORMULA: 
(HpxC6)  +  (dxC4)  =diagonal  pitch 


10 


LEGEND: 


Hp  =  horizontal  pitch  =3.3750 
d  =  diameter  of  rivet  =  .  8750 


horizontal  pitch  =   3 .  3750 
6 

20.2500 
3.5000 


EXAMPLE  :, 


diameter  of  rivet  =    .8750 
.  4 


3.5000 


10)23.7500(2.3750=diagonal  pitch 
20 

37 
30 

75 
70 


50 
50 


BUTT  JOINTS.  161 

Rule  to  find  distance  between  inner  rows  of  rivets  in  a  butt  joint, 
double  or  triple  riveted  chain  or  zig  zag  form.  Multiply  1  1  times 
the  pitch  plus  8  times  the  rivet  diameter  by  the  pitch,  plus  8  times 
the  rivet  diameter  ;  extract  square  root  of  this  product  and  divide  the 
sum  by  10. 

FORMULA: 

distance  between  rows  of  rivets 


10 

LEGEND: 

p  =  narrow  pitch  =3^=3.375 
d  =  diameter  of  rivet  =  .  875 

EXAMPLE: 

3.375=narrow  pitch 
11=11  times 


37.125 
7.000  .  875=  rivet  diam. 


44.125 

10.375  7 .  000  =  8  times  rivet  diam. 


220625  3.375  =  narrow  pitch 
3  08875  7  .  000  =  8  times  diam.  rivet 

13  2375 

441  25  10.375 

2)458.796875(21.419 


41)    58 
)   41 


424)  1779           10)21.419 

|  16%              2.1419=2^  approximate  dis- 

4281)  8368                            tanCG 

)  4281 


42829)   408775 

)   385461 
\ 

)    23314 

Rule  to  find  pitch  of  rivets  in  a -butt  joint  double  strap  and 
triple  riveted  inner  row :  Multiply  thickness  of  plate  by  3.5  and 
add  1^  of  an  inch  to  product. 

LEGEND:  FORMULA: 

T=thickness  of  plate  =  ^  =  .4375  TX3.5  +  !5/6=pitch 

p=pitch  3.5=3.5000 
1^=1.6250 


162  THE  BOILER. 


EXAMPLE: 

.4375  =  th*ickness  of  plate 
3.5 


21875 
13125 

1.53125 

i.625o  = 


3.15625=  3&  pitch 


Rule  to  find  plate  percentage  at  wide  pitch :  From  wide  pitch 
subtract  diameter  of  rivet  and  divide  this  product  by  wide  pitch  of 
rivet. 

FORMULA : 

WP— d 

= plate  percentage 


WP 

LEGEND: 


WP  =  wide  pitch  =  6 .  7500 

d  =  rivet  diameter  =      =  .  93  75 


EXAMPLE  : 

6 .  7500  =pitch  of  rivet 
.  9375  =diameter  of  rivet 


wide  pitch  =6.7500)5.  812500  (.  86  =plate .percentage  at  wide  pitch 
5   40000 


412500 
405000 

7500 


Rule  to  find  percentage  of  plate  at  narrow  pitch :  From  narrow 
pitch  subtract  rivet  diameter  and  divide  this  product  by  narrow 
pitch. 

FORMULA : 

NP— d 

—  =  plate  percentage 
NP 

LEGEND: 

NP=  narrow  pitch  =3.  5 000 
d  =  rivet  diameter  =||  = . 9375 


BUTT  JOINTS.  163 

EXAMPLE  : 

3  .  5000  =  narrow  pitch 
.9375  —rivet  diameter 


narrow  pitch -3.  5000) 2.  562500 (.73  =  plate   percentage  at    nar- 
2  45000  row  pitch 


112500 
105000 

7500 


Rule  to  find  safe  working  pressure  on  a  boiler  butt  joint  double 
strap,  triple  riveted :  Multiply  tensile  strength  of  material  by  the 
lowest  percentage  of  joint  and  this  sum  by  twice  the  thickness  of 
plate ;  divide  by  diameter  of  boiler  multiplied  by  factor  of  saftey. 


FORMULA: 
TSX%X(Tx2) 

DxF 
LEGEND: 

TS  =  tensile  strength  =60000 
%  = lowest  percentage  of  joint  =73% 

T  =  thickness  of  plate  =  ^  =  .  4375 

D  =  diameter  of  boiler  =  72" 

F  =  factor  of  safety  =5 

EXAMPLE: 


=safe  working  pressure 


60000  =  tensile  strength 

.  73  =  lowest  percentage  of  joint 


180000 
420000 

43800.00 

.8750=twice  thickness  of  plate 


219000000 

boiler  diam.  =    72     30660000 
factor  =     5  35040000 


360)38325.  JWW  (106  Ibs.  working  pressure 
360 


2325 
2160 

165 


164 


THE  BOILER. 
TRIPLE  RIVETED  BUTT  JOINTS. 


o 

^-,  c. 

0  « 


o's 


& 
f1 

1 


Yf 
\l 


X 

u 

A 


11 


14 
14 


9% 
LO 

LO 
11 


16 

16M 

18 

18 


3M 
3M 


3%    I 


674 
6M 


2^ 


87 
86 
88 
88 
87 
87 
86 
86 
86 
85 
84 


COMPUTING   STRENGTH    OF   A   BUTT   JOINT   DOUBLE   STRAP   AND   TRIPLE 

RIVETED. 


There  are  five  causes  for  failure  at  a  butt  joint  double  strap 
and  triple  riveted,  as  follows : 

First.     By  tearing  at  outer  row  of  rivets. 

Second.  By  shearing  of  four  rivets  in  double  shear  and  one  in  single 
shear. 

Third.  By  the  tearing  at  middle  row  of  rivets  and  the  shearing  of  one 
rivet. 

Fourth.     By  the  crushing  in  front  of  four  rivets  and  shearing  of  one  rivet. 

Fifth.  By  the  crushing  in  front  of  five  rivets,  four  through  strap,  the 
fifth  through  inner  covering  of  plate  only. 

LEGEND: 

D  =  diameter  of  boiler  =  72" 
ID  =  internal  diameter  of  boiler  =  71 . 1250 

F=factor  =  5 
TS  =  tensile  strength  =  60000 

P  =  pressure 

Pt  =  pitch  inner  row  =3^=3.375  .;i 

Po  =pitch  outer  row  =6%  =6.  750 
SS  =  shearing  strength  of  rivets  =38000 
CS  =  crushing  resistance  =95000 

T  ^thickness  of  plate  =TV  =  .  4375 

d  ^diameter  of  rivet  =  %  =  .  8750 
DH  =  diameter  of  rivet  hole  =  jf  =  .  9375 

A  =area  of  rivet  =  .  6903 
CP  =  cover  plate  or  thickness  of  strap  =  .  3750 


BUTT  JOINTS.  165 

First.  The  failure  by  tearing  at  the  outer  row  of  rivets,  the  resistance  is 
found  by  the  following  rule:  From  pitch  of  rivet  subtract  the 
diameter  of  rivet  and  multiply  by  thickness  of  plate  and  then  multi- 
ply by  tensile  strength  of  material. 

FORMULA: 
(Po— DH)  XTxTS  =net  section  of  plate 

EXAMPLE: 

6.  7 5 00=  wide  pitch 
.9375  =  diameter  of  rivet  hole 


5.8125 
.4375  =  thickness  of  plate 


290625 
406875 
174375 
2  32500 

2.54296875 

60000  =  tensile  strength  of  plate 


152578.  WWWW  Ibs.  -net  section  of  plate 

Second.     Shearing  of  four  rivets  in  double  shear  and  one  in  single  shear. 

FORMULA: 

A  X  N  X  DS  +  Id  of  SS  =  strength  of  rivets 
N  =  number  of  rivets  =4 
for  double  shear 

EXAMPLE: 

.  6903  =area  of  £f  rivet 

4  =  number  of  rivets,  double  shear 


area  of  rivet  =    .  6903  2.7612 

single  shearing  re-  =          38000  70300  =  strength  of  rivets  double  shear 
sistance 

55224000  8283600 

20709  193284 


26231. &W     194112. 

26231.         =  single  shearing    strength    one 

rivet 
220343  .   Ibs.  -strength  of  rivets 


Third.    Tearing  at  middle  row  of  rivets  and  shearing  of  one  rivet,  the  resist- 
ance is : 

FORMULA: 

(Po— 2DH)  XT  XTS   plus  (A  X SS)  =  resistance  to  tearing  of  plate  at  middle 

row  and  shearing  one  rivet 


166  THE  BOILER. 


EXAMPLE: 


6.  7 5 00=  wide  pitch 

1.8750=2  diameters  of  rivet  hole 

4.8750 
.4375  =  thickness  of  plate 

243750 
341250 
146250 
1  95000 

2.13281250 

60000=  tensile  strength 


127968.  10000000 
26231.  =shearing  strength  one  rivet  single 

shear 

154199.    Ibs.  =  resistance  to  tearing  at  middle  row 
and  shearing  one  rivet 


Fourth.     Crushing  in  front  of  four  rivets  and  shearing  of  one  rivet. 

FORMULA: 

(4DH  XT  xCS)plus  (A  XSS)  =  resistance  to  crushing  in  front  of  four  rivets 

and  shearing  one  rivet 

EXAMPLE: 

3 .  7500  =four  diameters  of  rivet  hole 
.4375  =  thickness  of  plate 


187500 
262500 
112500 
1  50000 

1.64062500 

95000  =  crushing  strength  of   rivet 

material 
820312500000 
14765625 


155859.J 
26231  =  shearing  strength  one  rivet  single 

shear 

182090.    Ibs.  =  resistance  to  crushing  in    front    of 
four  rivets  and  shearing  of  one 


Fifth.  Crushing  in  front  of  five  rivets,  four  thro  ugh  straps,  the  fifth  through 
inner  cover  plate  only,  the  resistance  is : 

FORMULA: 

(4DHXTXCS)  plus(DHxCPxCS)  =  resistance    to    crushing    of    plate    in 

front  of  five  rivets 


BUTT  JOINTS.  167 

EXAMPLE: 

diameter  of  rivet  hole  =  .  9375  3 .  7500  =  four  diameters  of  rivet  hole 

strap  thickness  =  .  3750  .  4375  =thickness  of  plate 

468750  187500 

65625  262500 

28125  112500 

1  50000 


crushing  strength      .35156250 


of  rivet  =  95000        1.64062500 

95000=  crushing    strength    of 
175781250000  rivet 
316406250                  820312500000 
1476562500 


33398.  WWWKt 

155859. 
33398 

189257  Ibs.  ^crushing  strain  of  plate  in 
front  of  five  rivets 

Rule  to  find  strength  of  strip  of  plate  at  wide  pitch. 

FORMULA: 

Po  XT  XTS  =strength  of  plate  at  wide  pitch 
EXAMPLE: 

6.7500=wide  pitch 
.4375  =  thickness  of  plate 

337500 
472500 
202500 
2  70000 


2.95312500 

60000=  tensile  strength 


177 18 7. £0000000  Ibs.  =  strength  of  strip  of 
plate  at  wide  pitch 

Rule  to  find  efficiency  of  joint  from  these  calculations. 

LEGEND: 

152578  =  strength  of  net  section  of  plate 
177187  =  strength  of  solid  plate 

EXAMPLE: 

177187)  152578 .  00  ( .  86  ^efficiency  of  joint 
141749  6 


10828  40 
10631  22 

197   18 


168  THE  BOILER. 

Rule  to  find  safe  working  pressure  from  efficiency  of  joint: 
Multiply  tensile  strength  of  plate  by  percentage  of  joint;  multiply 
this  sum  by  twice  thickness  of  plate  and  divide  product  by  diameter 
multiplied  by  factor  of  safety.  The  quotient  will  be  the  safe  work- 
ing pressure  of  boiler. 


FORMULA : 
TSX%X(2XT) 
IDXF 

EXAMPLE: 


=safe  working  pressure 


60000  =  tensile  strength  of  plate 
.  86  =  percentage  of  joint 


3600  00 
48000  0 

51600.00 

.8750  =  twice  thickness  of  plate 


internal  diam.  of  258  000000 

boiler  =    71.1250     3612  0000 
factor  of  safety  =  5  41280  000 


355.  6250)45150. 000000 (126.  95 -safe  working  pressure 
3556250 


9587500 
7112500 

24750000 
21337500 

34125000 
32006250 

21187500 
17781250 

3406250 


BUTT  JOINTS. 
QUADRUPLE-RIVETED  BUTT  JOINT. 


169 


© 


;©©©©©©©©• 
©©©©©©©©© 


:©©©©'©©©©: 


©     <£)    © 

©        © 


(S)     © 

..:®j 


Computing  strength  of  a  quadruple-riveted  butt  joint. 
Causes   for  possible   failure   in   a   butt   joint   double   strap 
quadruple  riveted: 


and 


First.       Tearing  of  plate  through  the  line  of  rivets  at  outer  row. 

Second.  Tearing  of  plate  through  line  of  rivets  at  se.cond  outer  row  and 

shearing  of  outer  row  of  rivets. 
Third.      Failure  of  plate  through  second  row  of  narrow  pitch  and  shearing 

of  the  two  outer  rows  of  rivets 
Fourth.  By  shearing  of  all  rivets. 

LEGEND: 

TS  = tensile  strength  =  60000 

SS  —shearing  strength  of  rivets  material  =38000 

CS  =  crushing  strain  of  material  =95000 

T  =  thickness  of  plate  =  ^  =  .  4375 

D  =  diameter  of  boiler  =  72" 

d  =  diameter  of  rivets  =  ^f  =.8125 
DH  =  diameter  of  rivet  hole  =  %  =  .  8750 

A  =area  of  rivets  =  %  =  .  6013 
PN  =  narrow  pitch  =  4^=4. 062  5 
PW=wide  pitch  =8^=8. 125 
Po  =  outside  pitch  =  1634"  =  16 .  2500  or  width  of  strap 

N  =  number  of  rivets 

In  connection  with  this  problem  it  is  assumed  that  the  straps 
or  cover  plates  are  three  fourths  (%)  the  thickness  of  shell  plates. 
Calculations  will  be  made  according  to  points  of  possible  failures. 


First.     Tearing  of  plate  through  the  line  of  rivets  at  outer  row, 

FORMULA: 
Po — d  =  section  of  plate  to  resist  tearing 


170  THE  BOILER. 


EXAMPLE: 

16  .  2500  =outside  pitch 

.8750  =  diameter  of        rivet  hole 


15  .  3750  ^section  of  plate  to  resist  tearing 
less  diameter  of  rivet 

To  calculate  the  efficiency  of  a  joint  it  will  be  necessary  to  find  out  strength 
of  solid  plate  in  strip  calculated. 

16.  2500  =pitch  outside  row 
.  4375  =  thickness  of  plate 

812500 
1137500 
487500 
650000 


7.10937500 

60000=  tensile  strength 


426562  .00000000  Ibs.  ^strength  of  solid  plate 
at  point  of  calculation. 

Second.     Tearing  of  plate  at  line  of  rivets  next  to  outer  row. 

FORMULA: 

(Po — 2DH)  XTxTS  +  SS  of  Id  =  resistance  to  tearing  of  plate  at  line  of  2d 

outer  row 

EXAMPLE: 

16 .  2500  =  outer  pitch  or  width  of  strip 
1.  7500  =two  diameters  of  rivet  hole 

14.5000 

.4375  =  thickness  of  plate 

725000 
1015000 
435000 
580000 


6.34375000 

60000  =  tensile  strength  of  plate 


380625.00000000 

380625  =lbs.  resistance  to  tearing  of  plate  at  second  outer  row 
22849  ^strength  of  the  one  rivet  in  outer  row 


403474  =lbs.  resistance  at  that  part  of  joint 

Third.     Failure  of  plate  through  second  row  of  rivets  in  narrow  pitch  and 
shearing  of  the  two  outer  rows  of  rivets. 

FORMULA: 
(Po— 4DH)  XTxTS  +  SSof  3d  =lbs.  resistance  in  width  of  strip 


BUTT  JOINTS.  171 

EXAMPLE: 

.6013  =area  of  one  rivet  16.  2500  =  width  of  strip  of  plate  outer  row 

38000  =  shearing  strength  3 .  5000  =  diameter  of  four  rivet  hole 

of  rivet 

48104000  12.7500 
18039  .4375  =  thickness  of  plate 


22849.4000  637500 

3  =three. rivets  892500 

382500 
68548.2000  510000 


5.57812500 

60000=  tensile  strength 


334687. 
68548  ^shearing  strength  of  three  rivets  in 

outer  rows 

403235  =lbs.   resistance  through  net    section 
of  plate 

Fourth.     Point  of  possible  failure  by  shearing  of  all  rivets.     There  being 
three  rivets  in  single  shear  and  eight  in  double  shear. 

FORMULA : 

AxSSxN  =  single  shear +  N  in  double  shear  =  shearing  strength  of  rivets  in 

joint 
EXAMPLE: 

.  6013  =area  of  %  rivet 

38000  ^shearing  strength  in  single 

shear 
48104000 
18038 


22849.4000 

3  =  number  of  rivets  in  single  shear 


68548  .  2000  =  shearing  strength  of  3  rivets  in 

single  shear 
.  6013  =area  of  %  rivet 

70300  =  shearing  strength  in  double  shear 

1803900 
420910 


42271.3900 

8  =  number  of  rivets 


338171 

Add  this  latter  product  to  the  sum  of  three  rivets  in  single  shear,  which 
gives  the  total  shearing  strength  of  rivets  in  joint. 

68548  =shearing  strength  of  3  rivets  in  single  shear 
338171  =shearing  strength  of  8  rivets  in  double  shear 

406719  Ibs.  =total  shearing  strength  of  rivets  in  joint 


172  THE  BOILER. 

To  get  the  efficiency  of  joint  at  this  point :     Divide  resistance  of  net  sec- 
tion of  plate  by  strength  of  solid  plate. 

EXAMPLE: 

403235  =  resistance  through  net  section  of  plate 
426562  =strength  of  solid  plate 

426562) 403235. 000 (. 945 =per  cent,  of  efficiency 
3839058 


1932920 
1706248 

2266720 
2132810 


133910 


Rule  to  find  safe  working  pressure  for  boiler  from  these  calculations: 
Multiply  tensile  strength  by  lowest  percentage  and  by  twice  thickness  of 
plate;  divide  this  product  by  diameter  multiplied  by  factor  of  safety. 


FORMULA: 
TSX%X2T 

DXF 
EXAMPLE: 


=  safe  working  pressure 


60000  =  tensile  strength 
.  945  = lowest  percentage  of  joint 


300000 
240000 
540000 

56700.000 

.  8750  =  twice  thickness  of  plate 


2835000000 

diam.  of  boiler  =  72"  396900000 
factor  of  safety  =    5   453600000 


360)49612.  5000000  (137.  8=lbs.  safe  workingpres- 
360  sure 


1361 
1080 

2812 
2520 

2925 
2880 

45 


BUTT  JOINTS.  173 

Butt  straps  or  cover  plates  of  a  quadruple  riveted  joint. 
Possible  causes  for  failure  of  butt  straps. 

First.       Both  straps  breaking  across  the  inner  row  of  rivets. 

Second.  The  plate  and  inner  strap  breaking  through  line  of  next  to  inner 
row  of  rivets. 

Third.  The  inner  strap  breaking  through  the  inner  row  of  rivets  and  shear- 
ing rivets. 

Fourth.  The  outer  strap  breaking  through  the  inside  row  of  rivets  and  shear- 
ing of  rivets. 

LEGEND: 

DH  -diameter  of  rivet  hole  =  %  =  .  8750 
TS  =  tensile  strength  -  60000 
Po  -outer  pitch  =  16 . 2500 
T  =  thickness  of  strap  =  .  3750 

First  possible  cause.     Both  straps  breaking  across  the  inner  row  of  rivets. 

FORMULA. 

(Po— 4DH)  XT  XN  XTS  =  tensile  strength  of  two  straps 
EXAMPLE: 

16.  2 5 00 -outer  pitch 
3.  5000  =four  rivet  hole  diameters 


12.7500 

.  3750  -thickness  of  strap 


6375000 
892500 
3  82500 


4. 78125000 -square    inches   of   material   at 

2     straps     (point  of  possible  fracture 

9.  56250000 -total  number  of  square  inches 
60000 -tensile  strength 

573750.00P00000  Ibs.  -tensile  strength  of  the  two  straps 
Showing  strength  of  straps  section  stronger  than  plate  section. 


Second.     Point  of  possible  failure — the  resistance  to  fracture  at  this  point 
is  greater  than  first  possible  cause. 


Third.     Possible  cause  for  failure  by  breaking  of  strap  through  line  of  rive; 
holes  at  inner  row. 

FORMULA: 

(Po— 4DH)  XT XTS  +  (N  X SS)  -total  resistance  to  tear    plate    and    shear 

rivets. 


1/4  THE  BOILER. 


EXAMPLE  : 


16. 2500 -outer  pitch 
3 .  5000  =four  rivet  hole  diameters 


12.7500 

.  3750  =  thickness  of  plate 


6375000 
892500 
3  82500 


4.78125000 

60000  =  tensile  strength 


182792  =  rivet  strength 

469667  Ibs.  =  resistance  to  tear  plate  and  shear 

rivets 

22849  —shearing  resistance  single  shear  of  7/8  rivets 
8  —number  of  rivets 


182792 


Fourth.     Point  of  possible  failure — same  as  third  point. 

These  calculations  show  the  straps  resistance  to  strain  exceeds  the  shell 
plate. 


CHAPTER  VIII. 


SAFE  WORKING  STEAM  PRESSURE  OF  BOILERS. 

AS   PRESCRIBED  BY  THE  BOARD  OF   SUPERVISING  INSPECTORS  OF   STEAM 
VESSELS  OF  THE   UNITED   STATES. 

The  working-  steam  pressure  of  a  boiler  shell  is  determined  by 
the  following  rule : 

Multiply  one-sixth  (1-6)  of  the  lowest  tensile  strength,  found 
stamped  on  any  plate  in  the  cylindrical  shell,  by  the  thickness  ex- 
pressed in  inches  or  parts  of  an  inch,  of  the  thinnest  plate  in  the 
same  cylindrical  shell,  and  divide  by  the  radius  or  half  diameter  — 
also  expressed  in  inches  —  and  the  sum  will  be  the  pressure  allow- 
able per  square  inch  of  surface  for  single  riveting,  to  which  add 
20  per  cent,  for  double  riveting  when  all  the  holes  have  been  fairly 
drilled  and  no  part  of  the  hole  has  been  punched. 

EXAMPLE. 

A  boiler  36  inches  in  diameter,  ]/±  inch  in  thickness,  tensile 
strength  60,000  pounds,  resolves  itself  into  the  following : 

1/6  of  60000  =  10000  X  .  25  =2500 

—  =  138 .  88  working  steam  pressure  allowable 
18 

for  single  riveting;  for  double  riveting  and  drilled  holes,  20  per  cent,  added 
=  166.65,  this  being  the  pressure  allowable  by  the  United  States  Marine 
Inspectors. 

On  the  following  pages  find  tables  of  pressure  allowed  on 
various  sizes  of  boiler  shells  for  50,000,  55,000  and  60,000  pounds 
tensile  strength  plates ;  also  a  table  which  simplifies  the  calculation. 
Steel  plate  having  a  tensile  strength  of  60,000  pounds  is  almost 
universally  used  by  builders  of  both  stationary  and  marine  boilers. 

175 


176 


THE  BOILER. 


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THE  STEAM  BOILER. 


181 


The  following  rules  and  tables  are  from  a  commercial  rating  and 
only  approximate. 

STANDARD   STEAM  BOILER  MEAUSUREMENTS. 

HORIZONTAL  TUBULAR. 

Based  on  12  square  feet  of  heating  surface  to  a  horse  power. 
A  Commercial  Rating. 


Size. 

Thick- 
ness. 

Boiler  with 

Hand  Holes. 

Boiler  with  Man  Holes. 

.2 

Z        j~ 
J         'fi 

"2 
ffi 

Size  of 
Dome. 

Tubes 
No. 

Dia. 

Heat. 
Surf, 
sq.  ft. 

Horse 
Power 

Tubes 
No. 

Heating. 
Surf. 
Dia.  sq.  ft. 

Horse 
Power. 

30 

6     y± 

3^ 

16x20 

19 

2i^ 

106 

9 

30 

8        J£ 

iMI  " 

16x20 

19 

2  % 

141 

12 

38 

2  % 

256 

21 

36 

8        M 

M 

18x20 

28 

3 

226 

19 

25 

3  % 

234 

20 

38 

2/4 

311 

26 

36 

10       K 

3^ 

18x20 

28 

3 

283 

24 

25 

3Y2 

292 

24 

42 

10        M 

% 

20x24 

38 

3 

372 

31 

34 

3% 

385 

32 

42 

12        M 

% 

20x24 

38 

3 

446 

37 

34 

3  H} 

462 

39 

42 

14        ^ 

N 

20x24 

38 

3 

520 

43 

34 

3  ^2 

539 

45 

42 

16        M 

% 

20x24 

38 

3 

595 

43 

34 

3  Yz 

616 

51 

44 

12        M 

% 

24x24 

48 

3 

544 

45 

38 

510 

43 

44 

14        K 

3% 

24x24 

48 

3   2 

635 

53 

38 

491 

41 

43 

12        A 

A 

24x24 

58 

3   2 

647 

54 

50 

3                572 

48 

50 

651 

54 

34 

3M           475 

40 

48 

14        A 

A 

24x24 

58 

3 

755 

63 

50 

3                667 

55 

50 

3  Y% 

759 

63 

34 

31A           547 

46 

48 

16        A 

A 

24x24 

58 

3 

862 

72 

50 

3                762 

64 

50 

3  y% 

867 

72 

34 

3YZ           633 

53 

48 

18        A 

A 

24x24 

58 

3 

970 

81 

50 

3                857 

71 

50 

3  /4 

976 

81 

34 

3YZ           712 

59 

71 

3 

912 

76 

59 

3                780 

65 

54 

14        A 

i^ 

30x30 

56 

3  ^2 

851 

71 

48 

3  Y%           748 

62 

43 

4 

763 

64 

40 

4                719 

60 

71 

3 

1042 

87 

59 

3                891 

74 

54 

16        A 

H 

30x30 

56 

3  ^2 

972 

81 

48 

3YZ           855 

71 

43 

4 

802 

67 

40 

4               821 

68 

The  above  table  is  based  on  rule  for  ascertaining  Heating  Surface. 


A  commercial  rating  of  boiler  horse  power  is  obtained  by  the 
following  rule : 

Add  to  two-thirds  of  boiler  shell  area,  tube  area  and  the 
area  of  one  head  (this  will  compensate  for  tubes  holes  in  both)  and 


182 


THE  BOILER. 


divide  product  by  unit  of  H.  P.  according  to  type  of  boiler.      (See 
table.) 


FORMULA: 
SA  +  TA  +  AH 


LEGEND: 

SA  =  shell  area 
TA  =tube  area 
AH  =area  of  head 
60"  =boiler  diameter 
16'  =  length 

46  4"     tubes 

HP  unit  =12  sq.  ft. 

diameter  of  head  = 


HP 


HP  unit 

EXAMPLE: 

3 . 1416  =  circumference  of  one  inch 
60"  =  diameter  of  boiler 


60" 
60 


188.4960 

192"  = length  of  boiler 


area  of  one  inch  = 


3769920 
16964640 

3600     1884960 
.7854 

3)36191. 2320  =area  of  boiler  shell 


14400 
18000 
28800 
25200 


12063  .  7440 
2 


area  head  =2827  .  4400 


24127  . 4880  =  %  of  boiler  shell  area 
2827 . 4400  =area  of  one  head 


26954.9280 
110986. 4448  =tube  area 


inches  per  square  ft.  =  144)  137941 .  3  72M  (957 .  9  =square  feet  of  heating 

1296  surface 


834 
720 

3. 1416=circumferenceof  lin.  1141     calculating  12  square 

4"=  tube  diameter           1008       ft.  per  HP  =  12)957.  9(79.  8 -HP 
84 


12.5664 

192"  =length  of  tube 


251328 
1130976 
125664 


1333 
1296 

37 


117 
108 

99 
96 


2412  .  7488  =  heating  surface  one  tube 
46  tubes 


144764928 
96509952 

110986.4448  =tube  area 


THE  STEAM  BOILER. 


183 


Heating  surface  proper  means  any  portion  of  the  boiler  where 
heat  is  applied  to  one  side  of  the  plate,  and  water  on  the  other. 

The  heating  surface  of  a  round  furnace  and  tubes  is  figured  by 
their  internal  diameter,  water  tubes  and  external  fired  surfaces 
are  measured  by  their  outside  diameter,  this  latter  being  the  surface 
heated  must  necessarily  be  considered  as  effective  heating  surface. 

The  heating  surface  of  boilers  can  readily  be  obtained  from  the 
following  table :  In  the  case  of  horizontal  tubular  bricked  in  boilers, 
two-thirds  of  the  boiler  shell,  the  whole  of  the  tube  surface,  and  the 
front  and  rear  head  deducting  area  of  tubes  and  surface  above  water- 
line  is  figured  as  effective  heating  surface. 


Diameter    of    boiler, 

inches 

26 

28 

30 

32 

34 

36 

38 

40 

42 

44 

46 

48 

Two-thirds      of      the 

heating   surface   of 

shell    per    foot    of 

length  

4.54 

4.89 

5  .  24 

5.59 

5.93 

6.29 

6.G3I   6.98 

7.331   7.68 

8.03 

8.38 

Diameter    of    boiler, 

inches  

50 

52 

54 

5G 

58 

GO 

62 

64 

66 

68 

70 

72 

Two-thirds      of      the 

l 

heating  surface  of 

i 

shell    per    foot    of  I 

I 

length  |8.73 

9.08 

9.42 

9.77110.12 

10.47110  82 

11.17111.52 

11  .87112.22 

12.57 

TYPES  OF  BOILERS  AND  ESTIMATED  GRATE  TO  HEATING  SURFACE  PER 
HORSE  POWER. 


Types. 

Square  feet  of 
Heating  Surface 
per  horse  power. 

Square  feet  of 
Heating  Surface 
to  one  foot  of  grate  . 

Cylinder 

6  to  10 

12  to  15 

Flue  .                                           

8  to  12 

20  to  25 

Horizontal  Tubular  
Water  Tube  
Vertical  

12  to  14 
11  to  12 
10  to  12 

25  to  35 
35  to  40 
25  to  30 

Internal  Fired  

12  to  15 

50  to  100 

RATIO  GRATE  SURFACE  TO  HORSE  POWER. 


Type  of  Boiler. 


Ratio. 


HT 4  to  6 

WT 3 

Loco .02  "  6 

Marine.  .  .  .  12 


HEATING  SURFACE  RATIO  TO  GRATE  SURFACE. 


HT 40  to  50 

WT 34  "  65 

Loco , 30  "  34 

Marine .  .28  "  32 


184 


THE  BOILER. 


COAL  AND  GRATE. 

The  average  consumption  of  coal  for  steam  boilers  is  12  pounds 
per  hour  for  each  square  foot  of  grate  surface. 

Western  coals,  having  a  large  amount  of  sulphur,  require  more 
space  in  furnace  and  more  air. 

Rule  to  find  area  of  grate  for  a  given  boiler: 

Divide  pounds  of  water  to  be  evaporated  per  hour  by  number  of 
pounds  of  water  evaporated  multiplied  by  number  of  pounds  of  coal 
burned  per  hour  per  square  foot  of  grate. 

FORMULA: 
number  of  Ibs.  of  water  evaporated  per  hour 


water  in  Ibs.  evap.   X  per  Ibs.  of  coal  per  hour 
LEGEND:  EXAMPLE: 


'area  of  grate 


2400  =lbs.  of  water  to  be 

evaporated 
12  =lbs.  of  coal  per  square 

foot  of  grate 
9  =lbs.  of  water 


108)2400  (22  square  feet  of  grate  required 
216 


240 
216 


24     12  Ibs.  of  coal  per  sq.  ft.  of  grate 
9  Ibs.  of  water  per  Ibs.  of  coal 

108  Ibs.  of  water  evaporated  per 
sq.  foot  of  grate 

TABLE  FOR  PRESSED  STEEL  BOILER  LUGS. 

Iron  rivets  have  a  shearing  strength  of  38000  Ibs. 
Steel    "  "  45000  " 

See  tables  for  boiler  weights  and  rivet  strength. 


Diameter 
of  boiler, 
inches. 

Height  of 
base  of 
lug  above 
center  of 
boiler. 

Width  of 
lug. 

Length  of 
lug  pro- 
jection. 

Height 
of  lug 
on 
boiler. 

Thick- 
ness. 

Weight, 
Ibs. 

30 

1 

7 

7 

7 

A 

6 

36 

2 

7 

7 

7 

M 

8 

42 

2j^ 

8 

8 

8 

L/ 

10  Vo 

48 

3^ 

8 

8 

8 

& 

14 

54 

10 

10 

10 

& 

20^ 

60 

4^ 

10 

10 

10 

3/£ 

23 

66 

4L/ 

12 

12 

12 

^8 

35 

72 

5 

12 

12 

12 

40 

78 

6 

12 

12 

12 

iHi 

45 

84 

7 

12 

12 

12 

* 

50 

THE  STEAM  BOILER. 


185 


WEIGHT  OF  HORIZONTAL  TUBULAR  BOILERS  FOR  125  LBS.  STEAM  PRESSURE 
COMPLETE  WITH  FITTINGS  FULL  OF  WATER. 


Diameter  of 
boiler,  inches 
Length  in  feet  .  . 
Weight    full    of 
water  

36 

8 

6,100 

36 
10 

7,600 

42 
10 

9,500 

42 
12 

10,600 

44 
12 

11,600 

48 
12 

13,400 

50 
13 

14,300 

54 
13 

15,400 

54 
15 

17,900 

60 
14 

20,900 

60 
15 

24,900 

Diameter  of 
boiler,  inches  . 
Length     in    feet 
Weight    full    of 
water  

60 
16 

27,300 

66 
16 

30,400 

66 
16 

35,100 

72 
16 

40,100 

72 
18 

44,100 

78 
18 

48,100 

78 
20 

56,100 

84 
18 

55,100 

84 
20 

67,100 

90 
18 

65,100 

90 
20 

75,100 

DIRECTIONS  FOR  SETTING  BOILERS. 

Make  the  excavation  to  a  depth  suitable  to  ground  that  boiler  is 
to  rest  upon  not  less  than  24  inches.  Build  foundation  walls  at  least 
12"  wider  than  walls  to  floor  level,  fronts  to  rest  upon  two  courses 
of  brick  above  the  floor  level.  Set  boiler  in  place  and  block  it  up 
three  or  four  inches  higher  than  it  is  to  remain,  the  back  side  of 
front  to  set  back  four  inches  from  front  edge  of  brick  work.  Carry 
up  the  side  and  end  walls  to  the  proper  height  for  the  resting  place 
of  brackets  (if  boiler  has  brackets  place  rollers  between  plates  and 
lugs)  leaving  space  so  that  walls  will  not  be  pushed  out  of  place  by 
expansion  of  boiler.  (Some  engineers  prefer  an  air  space  in  setting 
side  and  end  walls,  as  a  nonconductor  of  heat.)  The  walls  should 
be  tied  together  by  headers  and  run  every  eighteen  inches.  The 
headers  from  outside  walls  should  touch  those  of  inner  wall  and  not 
be  tied  together.  Fire  brick  in  the  furnace  should  be  laid  with  a 
course  of  headers  every  six  courses  so  that  the  wall  can  easily  be 
taken  out  and  repaired  at  any  time  when  necessary.  The  rear  con- 
nection or  back  arch  should  be  lined  with  fire  brick,  the  ends  of  arch 
resting  on  side  walls  and  the  arch  of  such  radius  to  permit  of  easy 
access  to  tubes  at  rear  head.  A  space  of  one  inch  should  be  left 
between  rear  end  of  boiler  and  inside  of  arch  so  that  the  expansion 
of  boiler  will  not  affect  brick  work  and  should  be  so  arranged  that 
it  can  be  removed  without  injury  to  walls.  It  is  preferable  when  cov- 
ering a  boiler  to  do  so  with  magnesia,  as  it  is  light,  a  non-conductor 
and  will  give  evidence  of  any  leakage  at  a  local  point  by  discoloration 
or  becoming  soft,  not  like  the  brick  covered  boiler  that  may  have 
leakage  many  feet  from  point  of  steam  issuing.  If  brick  is  to  be 
used  a  two  inch  space  should  be  left  between  boiler  and  brick  work. 


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THE  STEAM  BOILER. 


187 


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188 


THE  BOILER. 


MATERIALS  FOR  BRICKWORK  OF  REGULAR  TUBULAR  BOILERS. 
SINGLE  SETTING. 


Boilers. 

Common 
Brick. 

Fire 
Brick. 

Sand, 
bushels 

Cement, 
barrels. 

Fire 
Clay, 
Ibs. 

Lime, 
barrels. 

30  inches  x  8  feet 

5200 

320 

42 

5 

192 

2 

30   "   x  10  " 

5800 

320 

46 

53^ 

192 

2M 

36   "   x  8  " 

6200 

480 

50 

6 

288 

2^ 

36   "   x  9  " 

6600 

480 

53 

63^ 

288 

2% 

36   "   x  10  " 

7000 

480 

56 

7 

288 

36   "   x  12  " 

7800 

480 

62 

8 

288 

3M 

42   "   x  10  " 

10000 

720 

80 

10 

432 

4 

42   "   x  12  " 

10800 

720 

86 

11 

432 

4K 

42   "   x  14  " 

11600 

720 

92 

11M 

432 

^A 

42   "  •  x  16  " 

12400 

720 

99 

12^ 

432 

5 

48   "   x  10  " 

12500 

980 

100 

12H 

590 

5M 

48   "   x  12  " 

13200 

980 

108 

13  H 

590 

53^ 

48   "   x  14  " 

14200 

980 

116 

143^ 

590 

5M 

48   "   x  16  " 
54   "   x  12  " 

15200 
13800 

980 
1150 

124 
108 

153^ 
13M 

590 
690 

6 

$1A 

54   "   x  14  " 

14900 

1150 

117 

15 

690 

6 

54   "   x  16  " 

16000 

1150 

126 

16 

690 

6M 

60   "   x  10  " 

13500 

1280 

108 

133^ 

768 

53^ 

60   "   x  12  " 

14800 

1280 

118 

14M 

768 

6 

60   "   x  14  " 

16100 

1280 

128 

16 

768 

6^ 

60   "   x  16  " 

17400 

1280 

140 

173^ 

768 

7 

60   "   x  18  " 

18700 

1280 

148 

ISM 

768 

7^ 

66   "   x  16  " 

19700 

1400 

157 

19% 

840 

8 

72      x  16 

20800 

1550 

166 

20M 

930 

8K 

TWO  BOILERS  IN  A  BATTERY. 


30  inches  x  8  feet 

8900 

640 

70 

9 

384 

33^ 

30   "   x  10  " 

9600 

640 

76 

93^ 

384 

4 

36   "   x  8  " 

10500 

960 

84 

103/6 

576 

4M 

36   "   x  9  " 

11100 

960 

88 

11 

576 

4^ 

36   "   x  10  " 

11800 

960 

95 

12 

576 

4% 

36   "   x  12  " 

13000 

960 

104 

13 

576 

5M 

42   "   x  10  " 

17500 

1440 

140 

17H 

864 

7 

42   "   x  12  " 

18600 

1440 

148 

18^ 

864 

73^ 

42   "   x  14  " 

19900 

1440 

159 

20 

864 

8 

42   "   x  16  " 

21200 

1440 

168 

21 

864 

8K 

48   "   x  10  " 

21400 

1960 

170 

21H 

1180 

8M 

48   "   x  12  " 

22300 

1960 

178 

22  y3 

1180 

9 

48   "   x  14  " 

23900 

1960 

190 

24 

1180 

9^ 

48   "   x  16  " 

25100 

1960 

200 

25 

1180 

10 

54   "   x  12  " 

23300 

2300 

186 

233^ 

1380 

934 

54   "   x  14  " 

24800 

2300 

198 

25 

1380 

10 

•54   "   x  16  " 

26300 

2300 

210 

263^ 

1380 

103^ 

60   "   x  10  " 

22600 

2560 

180 

22^ 

1536 

9 

60   "   x  12  " 

24800 

2560 

198 

25 

1536 

10 

60   "   x  14  " 

26800 

2560 

214 

27 

1536 

10M 

60   "   x  16  " 

28900 

2560 

230 

29 

1536 

ii-H 

60   "   x  18  " 

31000 

2560 

248 

31 

1536 

123^ 

66   "   x  16  " 

33100 

2800 

264 

33 

1680 

13H 

72   "   x  16  (< 

34000 

3100 

272 

34 

1860 

13M 

THE  STEAM  BOILER.  189 

In  connection  with  boiler  setting  the  following  information  will 
be  useful : 

One  barrel  of  lime  will  lay  800  brick. 

Two  barrels  of  lime  will  lay  one  perch  rubble  stone. 

To  every  barrel  of  lime  estimate  about  ^  yards  of  good  sand 
for  brick  work. 

One  and  one  quarter  barrels  of  cement  and  three  quarters 
yard  of  sand  will  lay  100  feet  of  rubble  stone. 

Rule  to  find  number  of  brick  required:  Multiply  the  number 
of  cubic  feet  by  22.5. 

The  cubic  feet  is  found  by  multiplying  length  by  height,  then 
by  thickness. 

Bricks  are  usually  made  8"  X  4"  X  2"  requiring  27  bricks  to 
make  a  cubic  foot  without  mortar,  the  latter  is  estimated  to  fill  one 
sixth  of  space. 


CHIMNEYS  AND  STACKS. 

The  use  for  chimneys  is  necessary  in  many  plants  and  main- 
tained at  great  expense  of  heat  units  varying  as  high  as  30  per 
cent  of  fuel.  The  necessity  arises  from  following  causes,  viz. :  cost 
of  installing  modern  methods  and  the  necessity  for  a  chimney  to 
carry  off  obnoxious  gases. 

The  main  object  is  to  obtain  air  supply  for  combustion  of  fuel. 
Areas  for  chimneys  are  calculated  from  grate  area,  coal  burned  in 
a  certain  time  and  usually  a  ratio  of  8  to  1. 

The  temperatures  of  gases  escaping  up  a  chimney  will  depend 
on  the  material  and  distance  from  boilers — the  higher  the  tem- 
perature the  greater  the  velocity. 

The  weight  of  air  necessary  for  fuels  varies,  hence  the  necessity 
for  computing  for  the  maximum  amount. 

The  volume  of  air  is  proportional  to  its  temperature ;  24  pounds 
of  air  at  the  mean  of  the  atmosphere  temperature  is  300  cubic 
feet  and  at  a  temperature  of  550  degrees  F  is  twice  as  great. 

Rule  to  find  the  volume  of  one  pound  of  air  under  atmospheric 
pressure  for  a  given  temperature:  Divide  the  absolute  temperature 


190  THE  BOILER. 

of  air  byxthe  constant  40 ;  the  result  gives  the  volume  in  cubic  feet 
nearly. 

LEGEND:  EXAMPLE: 

Temp,  of  atmosphere  80  40)80  (2  =  volume  of  one  pound  in  cubic  feet 

Constant  40  80 


The  intensity  of  draft  is  independent  of  the  area  of  the  flue 
but  is  proportional  to  the  difference  in  weight  of  two  columns  of 
air  of  equal  base,  one  internal  and  one  external.  The  difference 
in  temperatures  between  the  volume  escaping  from  the  inside  and 
the  atmosphere  increases  the  draft  as  the  difference  between  the 
temperature  increases. 

The  atmospheric  pressure  or  draft  is  estimated  by  the  height  of 
an  equivalent  column  of  water. 


CONSIDERATIONS  GOVERNING  THE  HEIGHT  OF  A 

CHIMNEY. 

It  must  be  high  enough  to  give  the  required  intensity  of  draft 
at  an  economical  flue  temperature,  and  to  be  well  above  the  surround- 
ing objects;  increased  capacity  is  much  more  cheaply  gained  by 
increasing  the  area,  it  being  cheaper  to  build  nearer  the  ground,  and 
the  capacity  increases  with  the  square  of  the  diameter  and  only  as 
the  square  root  of  the  height.  If  of  brick  the  height  should  not 
exceed  ten  or  eleven  times  the  base,  on  account  of  stability. 

Rule  to  find  the  difference  in  pressure  to  be  expected  between  the 
inside  and  outside  of  a  chimney  for  a  given  height  and  temperature : 
Divide  39  by  the  absolute  (actual  temperature  Fahrenheit  plus  461) 
temperature  of  the  outside  air;  again,  divide  40  by  the  absolute 
average  temperature  of  the  gases  in  the  stack;  subtract  the  latter 
from  the  former  quotient,  multiply  the  remainder  by  the  height  of 
the  chimney  in  feet,  and  divide  by  5.2;  the  final  quotient  will  be 
the  draft  in  inches  in  water. 

The  following  table  will  give  the  draft  power  in  inches  of  water 
for  chimneys  of  specific  height  basing  the  temperature  as  follows : 

Escaping  gases  552  degrees  F. 

Atmospheric  temperature  62  degrees  F. 


THE  STEAM  BOILER. 


191 


Height  of 
Chimney 

Draft  Power 
in  Inches 

Theoretical  velocity  in  feet 
per  second. 

in  Feet. 

of  Water. 

Cold  Air 

Hot  Gases 

Entering. 

Escaping. 

10 

.073 

17.8 

35.6 

20 

.146 

25.3 

50.6 

30 

.219 

31.0 

62.0 

40 

.292 

35.7 

71.4 

50 

.365 

40.0 

80.0 

60 

.438 

43.8 

87.6 

70 

.511 

47.3 

94.6 

80 

.585 

50.6 

101.2 

90 

.657 

53.7 

107.4 

100 

.730 

56.5 

113.0 

120 

.876 

62.0 

124.0 

150 

1.095 

69.3 

138.6 

175 

1.277 

74.8 

149.6 

200 

1.460 

80.0 

160.0 

Draft  required  depends  largely  on  quality  and  nature  of  fuel 
and  rate  of  combustion ;  it  is  least  for  wood  and  free  burning  fuels 
and  greatest  for  fine  coal;  for  slack  coal  draft  equivalent  to  1J4 
inches  of  water  is  necessary. 

In  designing  height  of  chimney  it  is  the  aim  to  provide  for  an 
excess  of  demands  and  regulate  by  dampejs  to  amount  required. 

Increasing  height  will  increase  the  flow  of  escaping  gases. 

AREA  OF   CHIMNEY   WHEN    HORSE   POWER   IS   GIVEN. 

Three  horse  power  per  square  foot  of  grate  surface. 

Rule. —  Divide 'the  horse  power  by  3.33  times  the  square  root  ot 
the  height.  The  quotient  will  be  the  required  effective  area  in 
square  feet.  To  the  diameter  or  length  of  side  required  to  give 
this  area  add  two  inches  to  compensate  for  friction. 


HORSE    POWER   OF   A   GIVEN    CHIMNEY. 

Rule. —  From  the  area  in  square  feet  subtract  .6  of  the  square 
root  of  that  area  and  multiply  the  remainder  by  the  square  root  of 
the  height  and  by  3.33. 

Or: 

Multiply  the  area  in  square  inches  by  the  square  root  of  the 
height  in  feet  and  divide  by  40.  The  quotient  will  be  the  horse 
power. 


192 


THE  BOILER. 


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.^ 

THE  STEAM  BOILER. 
Following  is  a  table  by  Professor  Trowbridge : 


193 


Height  in  feet. 

Pounds  of  Coal  burned 
per  hour  per  square 
foot  of  section  of 
chimney. 

Pounds  of  Coal  burned 
per  hour  per  square 
foot,  the  ratio  of  grate  to 
chimney  be.  ing  8  to  1. 

20 

60 

7.5 

25 

68 

8.5 

30 

76 

9.5 

35 

84 

10.5 

40 

93 

11.6 

45 

99 

12.4 

50 

105 

13.1 

55 

111 

13.8 

60 

116 

14.5 

65 

121 

15.1 

70 

126 

15.8 

75 

131 

16.4 

80 

135 

16.9 

85 

139 

17.4 

90 

144 

18.0 

95 

148 

18.5 

100 

152 

19.0 

105 

156 

19.5 

110 

160 

20.0 

CHIMNEYS. 

Area  of  chimney  for  given  height  and  number  of  square  feet 
of  grate  surface  connected. 

Rule. —  Multiply  the  number  of  square  feet  of  grate  surface  by 
120,  and  divide  by  the  square  root  of  the  height.  The  quotient  will 
be  the  required  cross  section  in  square  inches.  See  table. 


194 


THE  BOILER. 


^ 

H 

8  g 

s  g 

s  I 

s  w 

11 

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51 

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g 

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CO 


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THE  STEAM  BOILER. 


195 


PROPORTIONS  OF  SELF-SUPPORTING  STEEL  STACKS. 


Diameter 

"o 

& 

«J 

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_  b 

"o 

Diameter 

at  Top  of 

Diameter 

15  c 

c 

u 

w^;  j£ 

1- 

~£  . 

r-; 

u.  ;i 

o  ~ 

f  ? 

at  Base. 

Bell 

at  Top  of 

t/3  ,  .2 

'£  • 

-5.-rc 

II 

1  1 

^ 

£< 

Portion. 

Stack. 

1  i'3 

%* 

P3  c 

o  -^  .5 

Q£ 

'Z 

On"5 

"3  5  J 

£•£ 

«> 

01 

gj 

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£  "  J 

100 

30 

70 

0.41 

0.25 

30 

7 

6 

4 

6 

3 

4 

20.6 

4500 

3500 

7.1 

115 

30- 

90 

0.53 

0.28 

34 

8 

6 

4 

8 

3 

4 

29.5 

5000 

5000 

10.0 

130 

30 

110 

0  .  65 

0.32 

38 

9 

0 

4 

9 

3 

4 

40.0 

7000 

6500 

13.0 

125 

33 

70 

0.41 

0.31 

36 

7 

4 

4 

9 

3 

7 

25.0 

5000 

4500 

8.8 

140 

33 

90 

).53 

0.35 

42 

8 

3 

5 

0 

3 

7 

34.5 

6000 

5500 

11.0 

160 

33 

110 

).65 

0.40 

46 

9 

3 

5 

2 

3 

7 

46.0 

7500 

7000 

14.1 

150 

36 

70 

0.41 

0.37 

44 

7 

7 

5 

0 

3 

10 

29.6 

5000 

5000 

9.6 

175 

36 

90 

0.53 

0.44 

52 

s 

6 

5 

2 

3 

10 

40.0 

7000 

6000 

11.6 

200 

36 

110 

0.65 

0.50 

58 

9 

6 

5 

4 

3 

10 

52.5 

8000 

8000 

15.0 

250 

42 

90 

0.53 

0.62 

74 

8 

9 

5 

6 

4 

4 

32.1 

7500 

6000 

12.3 

275 

42 

110 

0.65 

0.68 

80 

9 

3 

5 

8 

4 

4 

46.0 

9000 

8000 

16.2 

300 

42  130 

0.76 

0.75 

92 

10 

9 

6 

2 

4 

4 

63.3 

10500 

11000 

20.2 

350 

48 

90 

).53 

0.87 

104 

9 

2 

6 

5 

4 

10 

40.0 

8000 

7000 

13.6 

375 

48 

110 

0.65 

0.93 

110 

9 

9 

6 

9 

4 

10 

56.0 

10000 

9000 

18.1 

400 

48 

130 

0.76 

1.00 

118 

11 

4 

6 

8 

4 

10 

75.7 

12000 

12000 

21.8 

430 

54 

90 

0.53 

1.07 

126 

9 

8 

6 

6 

5 

4 

52.6 

9000 

7500 

15.3 

470 

54 

110 

0.65 

1.17 

138 

10 

8 

6 

8 

5 

4 

71.9 

11000 

10000 

20.1 

510 

54 

130 

0.76 

1.27 

150 

11 

9 

7 

2 

5 

4 

94.7 

13000 

13000 

24.0 

580 

60 

100 

).59 

1.45 

170 

10 

6 

7 

0 

5 

10 

67.3 

11000 

8000 

18.5 

675 

60 

125 

0.73 

1.62 

190 

12 

0 

7 

8 

5 

10 

97.0 

14000 

13000 

24.7 

700 

60 

150 

0.87 

1.75 

206 

13 

2 

7 

9 

5 

10 

122.0 

17000 

17000 

31.9 

700 

66 

100 

).59 

1.75 

206 

11 

0 

7 

6 

6 

4 

80.0 

12000 

9000 

20.8 

800 

66 

125 

0.73 

2  00 

234 

12 

6 

8 

2 

6 

4 

105.0 

15000 

15000 

26.3 

900 

66 

150 

0.87 

2.25 

264 

13 

8 

8 

4 

6 

4 

135  .  0 

18000 

20000 

34.4 

950 

72 

125 

0.65 

2.37 

280 

13 

0 

8 

8 

6 

10 

90.0 

16000 

11000 

27.2 

1050 

72 

150 

0.87 

2.67 

310 

14 

2 

8 

9 

6 

10 

113.0 

20000 

19000 

38.8 

1150 

72 

175 

1.03 

2.87 

326 

15 

3 

9 

0 

6 

10 

155.0 

23000 

26000 

42.3 

1150 

78 

1  25 

0.65 

2.87 

326 

13 

6 

9 

2 

7 

4 

105.0 

17000 

18000 

30.0 

1250 

78 

150 

0.87 

3.12 

368 

14 

8 

9 

4 

7 

4 

141.0 

21000 

24000 

38.9 

1350 

78 

175 

1.03 

3.37 

396 

15 

9 

9 

6 

7 

4 

185.0 

24000 

29000 

45.0 

1400 

84 

130 

0.76 

3.50 

412 

14 

0 

9 

8 

7 

10 

116.0 

19000 

21000 

33.8 

1550 

84 

It).', 

0.97 

3.87 

456 

15 

4 

9 

9 

7 

10 

161.0 

25000 

28000 

44.7 

1700 

84 

200 

1.18 

4.25 

500 

16 

9 

10 

0 

7 

10 

217.0 

30000 

34000 

54.3 

1800 

96 

140 

0.82 

4.501  530 

15 

4 

10 

8 

8 

10 

140.0 

24000 

25000 

42.4 

2100 

96 

180 

1.06 

5.25 

620 

17 

0 

10 

9 

8 

10 

200.0 

30000 

31000 

52.9 

2300 

96 

•)•;() 

1.30 

5.75 

676 

18 

8 

11 

0 

8 

10 

273.0 

37000 

42000 

65.3 

2400 

108 

150 

0.87 

6.00 

706 

16 

9 

11 

9 

9 

10 

175.0 

28000 

31000 

49.9 

2700 

108 

190 

1.12 

6.75 

794 

18 

6 

12 

0 

9 

10 

242.0 

35000 

37000 

62.3 

3000 

108 

240 

1.41 

7.50 

882 

20 

6 

12 

2 

9 

10 

325.0 

45000 

48000 

89.0 

3000 

120 

150 

0.87 

7.50 

882 

17 

9 

12 

9 

10 

10 

262.0 

31000 

35000 

53.9 

3500 

120 

200 

1.18 

8.75 

1030 

19 

9 

13 

0 

10 

10 

304.0 

40000 

47000 

71.0 

3900 

120 

250 

1.48 

9.75 

1148 

21 

9 

13 

2 

10 

10 

400.0 

51000 

60000 

94.8 

4200 

132 

200 

1.18 

10.50 

1236 

20 

9 

14 

0 

11 

10 

294.0 

45000 

50000 

77.2 

4700 

132 

250 

1.48 

11.75 

1382 

23 

4 

14 

4 

11 

10 

400.0 

56000 

62000 

100.5 

5200 

132 

300 

1.67|13.00 

1528 

25 

0 

14 

8 

11 

10 

530.0 

67000 

75000 

140.7 

196  THE  BOILER. 

SMOKE  STACKS. 
APPROXIMATE  WEIGHT  IN  POUNDS  OF  ONE  FOOT  OF  STACK. 


Diameter, 
inches. 

THICKNESS  OF  MATERIAL. 

No.  16. 

No.  14. 

No.  12. 

No.  10. 

No.  8. 

Weight. 

Weight. 

Weight. 

Weight. 

Weight. 

10 

8 

10 

13 

16 

\9 

12 

9 

12 

14 

19 

23 

14 

11 

14 

16 

22 

27 

16 

12 

16 

20 

25 

31 

18 

14 

18 

23 

28 

35 

20 

15 

19 

25 

31 

38 

22 

17 

21 

28 

34 

42 

24 

18 

23 

30 

36 

45 

26 

19 

24 

32 

40 

48 

28 

21 

26 

35 

43 

52 

30 

22 

28 

37 

46 

56 

32 

23 

30 

39 

48 

58 

34 

24 

31 

41 

50 

60 

36 

26 

32 

43 

.52 

63 

38 

27 

34 

44 

54 

66 

40 

29 

36 

47 

57 

70 

42 

31 

38 

49 

60 

74 

44 

33 

41 

54 

66 

81 

48 

35 

45 

59 

72 

89 

54 

38 

48 

64 

82 

97 

60 

42 

53 

71 

90 

108 

66 

45 

59 

77 

98 

117 

72 

'51 

65 

86 

110 

131 

78 

58 

74 

98 

120 

150 

84 

62 

80 

105 

130 

160 

96 

72 

92 

130 

148 

180 

THE  STEAM  BOILER. 


197 


I       * 

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of  shell,  inches  . 
shell,  inches 
ubes,  inches.  . 
2-inch  tubes  . 
f  shell,  inches 
of  heads,  inche 
urnace,  inches 
f  furnace,  inc 
rface,  square  f 
r  safety-valve 
-off,  inches  .. 


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B   - 


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1 


198 


THE  BOILER. 


CAPACITIES  OF  BOILERS    FOR  Low  PRESSURE  STEAM  HEATING  APPARATUS. 


Boiler  Surface, 
square  feet. 

Total  Direct  Radiation, 
square  feet. 

Direct  Radiation 
per  square  foot  of 
Boiler  Surface. 

40 

168 

4.20 

50 

218 

4.36 

60 

272 

4.53 

80 

384 

4.80 

100 

504 

5.04 

120 

626 

5.21 

140 

752 

5.37 

152 

830 

5.46 

172 

962 

5.60 

194 

1114 

5.74 

211 

1232 

5.84 

252 

1522 

6.04 

292 

1816 

6.21 

295 

1840 

6.23 

347 

2240 

6.45 

399 

2642 

6.62 

421 

2820 

6.69 

482 

3321 

6.89 

541 

3818 

7.05 

580 

4247 

7.37 

720 

6210 

8.46 

The  quantities  of  radiation  in  the  above  table  are  exclusive  of  all  piping. 
One  square  foot  of   indirect  requires  the  same  boiler  capacity  as  1^ 
square  feet  of  direct  radiation. 

TO  DETERMINE  THE  SIZE  OF  STEAM  PIPE  MAINS  FOR  VARYING 
RADIATION. 

For  every  100  square  feet  of  radiating  surface,  allow  the  area 
of  a  one-inch  pipe  (.7854  square  inches). 

LIST  OF  SIZES  OF  STEAM  MAINS. 


Radiation, 

square  feet. 

One  Pipe  Work, 
inches. 

Two  Pipe  Work,  inches. 

40  t 

o   50 

1 

MX  Y± 

100 

125 

m 

1  x  M 

125 

250 

m 

iMxi 

250 

400 

2 

i^xi  M 

400 

650 

2^ 

2  xl^ 

650 

900 

3 

2^x2 

900 

1250 

3^ 

3  x2^ 

1250 

1600 

4 

3^x3 

1600 

2050 

4^ 

4  x3^ 

2050 

2500 

4^x4 

2500 

3600 

6 

5  x4^ 

3600 

5000 

7 

6  x5 

5000 

6500 

8 

7  x6 

6500 

8100 

9 

8  x6 

8100 

10000 

10 

9  x6 

THE  STEAM  BOILER. 


199 


Under  ordinary  conditions,  one  square  foot  of  direct  radiation 
surface  will  heat  approximately  in: 


Bath-room  ............................................ 

Living-room  .......................................... 

Living-room,  exposures,  ordinary  amount  of  glass  ........... 

Halls  ............................................  50  to 

Sleeping  rooms  ...................................  55   " 

School-rooms  ...  ..................................  60  " 

Churches  and  auditoriums  of  large  cubic  contents  and 


with  high  ceilings  .............................  65 

Factories  and  work-shops 


75 


40  cubic  feet. 

50        " 

60       " 

70 

70 

80 

100 
150 


CAPACITIES  OF  BOILERS  FOR  HOT  WATER  HEATING  APPARATUS. 


Boiler  Surface, 
square  feet. 

Total  Direct  Radiation, 
square  feet. 

Direct  Radiation 
per  square  foot  of 
boiler  surface. 

20 

110 

5.50 

30 

181 

6.03 

40 

257 

6.42 

50 

338 

6.76 

60 

425 

7.08 

70 

512 

7.46 

80 

603 

7.54 

90 

695 

7.72 

100 

792 

7.92 

120 

991 

8.26 

140 

1198 

8.56 

159 

1400 

8.80 

199 

1842 

9.25 

225 

2142 

9.52 

279 

2788 

9.99 

323 

3332 

10.31 

372 

3976 

10.68 

453 

5065 

11.18 

517 

5938 

11.48 

The  quantities  of  radiation  in  the  above  table  are  exclusive  of  all 

piping- 
One  square  foot  of  indirect  requires  the  same  boiler  capacity  as 
\Y-2.  square  feet  of  direct  radiation. 


CHAPTER  IX. 


SAFETY  VALVES. 

A  safety  valve  should  have  area  sufficient  for  the  escape  of 
steam  with  rapidity  to  prevent  the  raising  of  steam  to  exceed  10 
per  cent  of  pressure  allowed  and  calculations  should  be  from  a 
standard,  the  maximum  water  that  could  be  evaporated  per  pounds 
of  fuel- 
Any  spring-loaded  safety  valve  constructed  so  as  to  give  an 
increased  lift  by  the  operation  of  steam,  after  being  raised  from 
its  seat,  or  any  spring-loaded  safety  valve  constructed  in  any  other 
manner  so  as  to  give  an  effective  area  equal  to  that  of  the  afore- 
mentioned spring-loaded  safety  valve,  may  be  used  in  lieu  of  the 
common  lever-weighted  valve  on  all  boilers  on  steam  vessels,  and 
each  spring-loaded  valve  shall  be  supplied  with  a  lever  that  will  raise 
the  valve  from  its  seat  a  distance  of  not  less  than  that  equal  to 
one-eighth  of  the  diameter  of  the  valve  opening;  but  in  no  case 
shall  any  spring-loaded  safety  valve  be  used  in  lieu  of  the  lever- 
weighted  safety  valve  without  first  having  been  approved  by  the 
Board  of  Supervising  Inspectors. 

The  valves  shall  be  so  arranged  that  each  boiler  shall  have  at 
least  one  separate  safety  valve,  unless  the  arrangement  is  such  as 
to  preclude  the  possibility  of  shutting  off  the  communication  of  any 
boiler  with  the  safety  valve  or  valves  employed.  This  arrangement 
shall  also  apply  to  lock-up  safety  valves  when  they  are  employed. 

The  use  of  two  safety  valves  may  be  allowed  on  any  boiler, 
provided  the  combined  area  of  such  valves  is  equal  to  that  required 
by  rule  for  one  such  valve.  Whenever  the  area  of  a  safety  valve, 
as  found  by  the  rule  of  this  section  will  be  greater  than  that  cor- 

200 


TESTS  AND  INSPECTION.  201 

responding  to  6  inches  in  diameter,  two  or  more  safety  valves,  the 
combined  area  of  which  shall  be  equal  at  least  to  the  area  required, 
must  be  used. 


EXAMPLES: 
Boiler  pressure  =75  pounds  per  square  inch  (gauge ) . 

2  furnaces:     Grate    surface  =2x5    feet  6    inches    long X 3  feet  wide  = 
33  square  feet. 

Water  evaporated  per  pound  of  coal  =  8  pounds. 

Coal  burned  per  square  foot  grate  surface  per  hour  =  12^  pounds. 

Evaporation  per  square  foot  grate  surface  per  hour  =  8X12^  =100  Ibs. 

Hence  W  =  100  and  gauge  pressure  =75  pounds. 

From  table  the  corresponding  value  of  a  is  .230  square  inches. 

Therefore  area  of  safety  valve  =33  X.23  =7.59  square  inches. 

For  which  the  diameter  is  3^  inches  nearly. 

Boiler  pressure  =215  pounds. 

6  furnaces:     Grate  surface  =6X5  feet   6  inches  long X 3  feet  4  inches 
wide  =110  square  feet. 

Water  evaporated  per  pound  coal  =  10  pounds. 

Coal  burned  per  square  foot  grate  surface  per  hour  =  30  pounds. 

Evaporation  per  square  foot  grate  surface  per  hour  =  10  X  30  =300  Ibs. 

Hence  W  =300,  gauge  pressure  =215,  and  a  =.270  (from  table). 

Therefore  area  of  safety  valve  =  110 X. 270  =29.7  square  inches,  which 
is  too  large  for  one  valve.     Use  two. 
29.7 

—  =  14.85  square  inches.     Diameter  =  4 %  inches. 


Rule  to  determine  the  area  of  a  safety  valve  for  boiler  using  oil 
as  fuel  or  for  boilers  designed  for  any  evaporation  per  hour : 

Divide  the  total  number  of  pounds  of  water  evaporated  per  hour 
by  any  number  of  pounds  of  water  evaporated  per  square  foot  of 
grate  surface  per  hour  (W)  taken  from,  and  within  the  limits  of, 
the  table.  This  will  give  the  equivalent  number  of  square  feet  of 
grate  surface  for  boiler  for  estimating  the  area  of  valve.  Then 
apply  the  table  as  in  previous  examples. 

The  areas  of  all  safety  valves  on  boilers  contracted  for  or  the 
construction  of  which  commenced  on  or  after  June  1,  1904,  shall  be 
determined  in  accordance  with  the  following  formula  and  table : 


202  THE  BOILER. 

EXAMPLE. 

Required  the  area  of  a  safety  valve  for  a  boiler  using  oil  as  fuel, 
designed  to  evaporate  8,000  pounds  of  water  per  hour,  at  175 
pounds  gauge  pressure. 

Make  W=200. 
8,000 

—  =  40,  the  equivalent  grate  surface,  in  square  feet. 
200 

For  gauge  pre:sure  =  175  pounds  and  W=200  from  table,  a  =.218 
square  inch.  .218x40=8.72  square  inches,  the  total  area  of  safety  valve 
required  for  this  boiler,  for  which  the  diameter  is  3jf  square  inches  nearly. 

From  which  formula  the  areas  required  per  square  foot  of  grate 
surface  in  the  following  table  are  found  by  assuming  the  different 
values  of  W  and  P. 

The  figures  (a)  in  table  multiplied  by  square  feet  of  grate 
surface  give  the  area  of  safety  valve  or  valves  required. 

When  these  calculations  result  in  an  odd  size  of  safety  valve,  use 
next  larger  standard  size. 


TESTS  AND  INSPECTION. 


203 


r  (W)  =  pounds  water  eva 
rface  per  hour. 


pounds  per  square  foot  of  grate  surface  per  h 
X  pounds  coal  burned  per  square  foot  grate 


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204 


THE  BOILER. 


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13 


TESTS  AND  INSPECTION.  205 

Rule  to  find  area  of  pop  safety  valve  computed  from  grate  sur- 
face, water  evaporation  and  pressure :  Multiply  constant  .2074  by 
water  evaporated  per  pound  of  coal  per  hour  and  divide  by  working- 
pressure  ;  this  gives  area  of  safety  valve  per  square  foot  of  grate 
surface.  Multiplying  this  result  by  total  .grate  surface  gives  re- 
quired area  of  safety  valve  for  furnace  grate  area. 

FORMULA: 
.2074XW 

—  =area  of  safety  valve  per  square  foot  of  grate  area 


LEGEND: 

C=  constant  =  .2074 
W  =  pounds  of  water  evaporated  per  square  foot  of  grate  surface  per  hour 

8  pounds  of  water  per  pound  of  coal. 

P=absolute  pressure  plus  15  pounds  atmospheric  pressure  =90  pounds. 
G  = grate  surface  =30  feet. 
Coal  burned  per  square  foot  of  grate  per  hour  =  12.5  pounds. 


EXAMPLE: 


Ibs.  of  coal  burned  per  square 

foot  of  grate  per  hour  =  12.5 

water  evaporated  =        8 


100.0 

.2074=  constant 

100  =lbs.  of  water  evap.  per  hour 


working  pressure  =90)20.  7400  (.  2304  =area  of  valve  per  1 

18  0  square  foot  of  grate 

2   74 
2   70 


400 
360 

40 

.  2304    =area  of  valve  %j  "" 

30  =  total  square  feet  of  grate  surface 

6 .  9120  =3"  diameter  valve  required 


206  THE  BOILER. 

REQUIREMENTS   IN   CONSTRUCTION  OF   LEVER-SAFETY  VALVES. 

All  the  points  of  bearing  on  lever  must  be  in  the  same  plane. 

The  distance  of  the  fulcrum  must  in  no  case  be  less  than  the 
diameter  of  the  valve  opening. 

The  length  of  the  lever  should  not  exceed  the  distance  of  the 
fulcrum  multiplied  by  ten. 

The  width  of  the  bearings  of  the  fulcrum  must  not  be  less  than 
three-fourths  of  1  inch. 

The  length  of  the  fulcrum  link  should  not  be  less  than  4  inches. 

In  all  cases  the  weight  must  be  adjusted  on  the  lever  to  the 
pressure  of  steam  allowed  in  each  case  by  a  correct  steam  gauge 
attached  to  the  boiler.  The  weight  must  then  be  securely  fastened 
in  its  position  and  the  lever  marked  for  the  purpose  of  facilitating 
the  replacing  of  the  weight  should  it  be  necessary  to  remove  the 
same,  and  in  no  case  shall  a  line  or  any  other  device  be  attached  to 
the  lever  or  weight  except  in  such  manner  as  will  enable  the 
engineer  to  raise  the  valve  from  its  seat. 

When  safety  valve  is  blown  off  always  note  pressure  on  gauge ; 
if  there  is  a  difference,  seek  the  cause  and  adjust  the  gauge  or  valve 
until  they  are  as  intended. 

The  lever  safety  valve,  while  being  very  extensively  used,  is  not 
perfect  in  action  or  operation,  in  not  seating  itself  until  pressure  has 
been  reduced  considerable  below  point  it  is  set  at. 

The  following  rules  are  used  in  determining  values,  viz. : 
pressure,  length  of  lever  and  weight  of  ball. 

Rule  to  find  weight  of  ball  when  pressure,  length  of  lever  and 
area  of  valve  is  known :  Multiply  pressure  in  pounds  by  area  of 
valve  in  inches  and  multiply  this  product  by  distance  of  valve  center 
to  fulcrum ;  subtract  weight  of  lever  from  this  product  and  divide 
sum  by  length  of  lever. 

LEGEND: 

Va  = valve  area  =  12 .  5664  =4"  valve 

L=length  of  lever  =  30" 
W  =  weight  of  lever  =20  Ibs. 

d  =  distance  valve  center  to  fulcrum  =4" 

P  =  pressure  =100  Ibs. 

FORMULA: 

PxVaXd— W 

—  =  weight  required  for  ball 


TESTS  AND  INSPECTION.  207 

EXAMPLE: 

12.5664  —  4"  valve  area 
100  =  pressure 


1256.6400 

4=  distance   valve   center   to   ful- 


crum 


5026.5600 

20.  ==  weight  of  lever 


length  of  lever  =30") 5006.  5600  (166.  8853   or   167  Ibs.   nearly 
30  weight  of  ball 

200 
180 


206 
180 

265 
240 


256 
240 

160 
150 


100 
90 

10 

Rule  to  find  length  of  lever  when  pressure  and  weight  of  ball 
and  area  of  valve  is  given:  Multiply  area  of  valve  by  pressure  in 
pounds  and  by  distance  of  center  of  valve  to  fulcrum ;  to  this  product 
add  weight  of  lever ;  divide  by  weight  of  ball. 

FORMULA: 
VaXPXd  +  W 

—  =  length  of  lever 
Wt 

EXAMPLE 
Wt=  weight  of  ball  =  166. 8853  Ibs. 

12 .  5664  =  valve  area 

100  =lbs.  pressure 


1256.6400 

4"  =  valve  center  to  fulcrum 


5026.5600 

20.  =  weight  of  lever 


weight  of  ball  -166.  8853)5046.  5600  (30  =length  of  lever 
5006  559 


40  0010 


208  THE  BOILER. 

Rule  to  find  pressure  a  safety  valve  will  blow  off  at  when  weight 
of  ball,  length  of  lever  and  distance  of  valve  center  to  fulcrum  are 
known:  Multiply  weight  of  ball  by  length  of  lever,  add  weight  of 
lever  to  this  and  divide  by  valve  area  multiplied  by  distance  of  valve 
center  to  fulcrum ;  the  quotient  will  be  pressure  in  pounds. 

FORMULA: 
WtXL  +  W 

—  =  pressure 
VaXd 

EXAMPLE  : 
166 .  8853  = weight  of  ball 

30"  =  length  of  lever 

valve  area  =12.  5664  5006.5590 

distance  ==  4"     20.  =  weight  of  lever 


50 . 2656) 5026 .55900 (99 . 9  or  100  pounds 

4523   904  pressure  nearly 

502  6550 
452  3904 


50  26460 
45  23904 

5  02556 

Extracts  from  U.  S.  Government  rules  and  regulations,  pre- 
scribed by  the  Board  of  Supervising  Inspectors,  as  amended  Janu- 
ary, 1907: 

"  No  engineer's  license  shall  be  issued  hereafter  or  grade  in- 
creased except  upon. written  examination,  which  written  examination 
shall  be  placed  on  file  as  records  of  the  office  of  the  inspectors 
issuing  said  license.  When  any  person  makes  application  for  license 
it  shall  be  the  duty  of  local  inspectors  to  give  the  applicant  the 
required  examination  as  soon  as  practicable." 

CLASSIFICATION -OF  ENGINEERS. 

CHIEF. 

Chief  engineer  of  ocean  steamers. 

Chief  engineer  of  condensing  lake,  bay  and  sound  steamers. 

Chief  engineer  of  noncondensing  lake,  bay   and  sound  steamers. 

Chief  engineer  of  condensing  river  steamers. 

Chief  engineer  of  noncondensing  river  steamers. 


TESTS  AND  INSPECTION.  209 

Any  person  holding"  chief  engineer's  license  shall  be  permitted 
to  act  as  first  assistant  on  any  steamer  of  double  the  tonnage  of 
same  class  named  in  said  chief's  license. 

Engineers  of  all  classifications  may  be  allowed  to  pursue  their 
profession  upon  all  waters  of  the  United  States  in  the  class  for 
which  they  are  licensed. 

FIRST    ASSISTANT. 

First  assistant  engineer  of  ocean  steamers. 

First  assistant  engineer  of  condensing  lake,  bay  and  sound 
steamers. 

First  assistant  engineer  of  noncondensing  lake,  bay  and  sound 
steamers. 

First  assistant  engineer  of  condensing  river  steamers. 

First  assistant  engineer  of  noncondensing  river  steamers. 

Engineers  of  lake,  bay  and  sound  steamers,  who  have  actually 
performed  the  duties  of  engineer  for  a  period  of  three  years,  shall 
be  entitled  to  examination  for  engineer  of  ocean  steamers,  applicant 
to  be  examined  in  the  use  of  salt  water,  method  employed  in  regu- 
lating the  density  of  the  water  in  boilers,  the  application  of  the 
hydrometer  in  determining  the  density  of  sea  water  and  the  prin- 
ciple of  constructing  the  instrument ;  and  shall  be  granted  such 
grade  as  the  inspectors  having  jurisdiction  on  the  Great  Lakes 'and 
seaboard  may  find  him  competent  to  fill. 

Any  assistant  engineer  of  steamers  of  1,500  gross  tons  and  over, 
having  had  actual  service  in  that  position  for  one  year,  may,  if  the 
local  inspectors,  in  their  judgment,  deem  it  advisable,  have  his 
license  indorsed  to  act  as  chief  engineer  on  lake,  bay,  sound,  or  river 
steamers  of  750  gross  tons  or  under. 

Any  person  having  had  a  first  assistant  engineer's  license  for  two 
years  and  having  had  two  years'  experience  as  second  assistant 
engineer,  shall  be  eligible  for  examination  for  chief  engineer's 
license. 

SECOND    ASSISTANT. 

Second  assistant  engineer  of  ocean  steamers. 

Second  assistant  engineer  of  condensing  lake,  bay  and  sound 
steamers. 

Second  assistant  engineer  of  noncondensing  lake,  bay  and  sound 
steamers. 


210  THE  BOILER. 

Second  assistant  engineer  of  condensing  river  steamers. 

Any  person  having  had  a  second  assistant  engineer's  license 
for  two  years  and  having  had  two  years'  experience  as  third 
assistant  engineer,  shall  be  eligible  for  examination  for  first  assistant 
engineer's  license. 

THIRD    ASSISTANT. 

Third  assistant  engineer  of  ocean  steamers. 

Third  assistant  engineer  of  condensing  lake,  bay  and  sound 
steamers. 

First,  second,  and  third  assistant  engineers  may  act  as  such  on 
any  steamer  of  the  grade  of  which  they  hold  license,  or  as  such 
assistant  engineer  on  any  steamer  of  a  lower  grade  than  those 
to  which  they  hold  a  license. 

Any  person  having  a  third  assistant  engineer's  license  for  two 
years  and  having  had  two  years'  experience  as  oiler  or  water  tender 
since  receiving  said  license,  shall  be  eligible  for  examination  for 
second  assistant  engineer's  license. 

Inspectors  may  designate  upon  the  certificate  of  any  chief  or 
assistant  engineer  the  tonnage  of  the  vessel  on  which  he  may  act. 

Any  assistant  engineer  may  act  as  engineer  in  charge  on  steam- 
ers of  100  tons  and  under.  In  all  cases  where  an  assistant  engineer 
is  permitted  to  act  as  engineer  in  charge,  the  inspectors  shall  so 
state  on  the  face  of  his  certificate  of  license  without  further  ex- 
amination. 

It  shall  be  the  duty  of  an  engineer  when  he  assumes  charge 
of  the  boilers  and  machinery  of  a  steamer  to  forthwith  thoroughly 
examine  the  same  and  if  he  finds  any  part  thereof  in  bad  condition, 
caused  by  neglect  or  inattention  on  the  part  of  his  predecessor,  he 
shall  immediately  report  the  facts  to  the  master,  owner,  or  agent 
and  to  the  local  inspectors  of  the  district,  who  shall  thereupon  in- 
vestigate the  matter  and  if  the  former  engineer  has  been  culpably 
derelict  of  his  duty,  they  shall  suspend  or  revoke  his  license. 

Before  making  general  repairs  to  a  boiler  of  a  steam  vessel  the 
engineer  in  charge  of  such  steamer  shall  report,  in  writing,  the 
nature  of  such  repairs  to  the  local  inspector  of  the  district  wherein 
such  repairs  are  to  be  made. 

And  it  shall  be  the  duty  of  all  engineers  when  an  accident 
occurs  to  the  boilers  or  machinery  in  their  charge  tending  to  render 


TESTS  AND  INSPECTION.  211 

the  further  use  of  such  boilers  or  machinery  unsafe  until  repairs 
are  made,  or  when,  by  reason  of  ordinary  wear,  such  boilers  or 
machinery  have  become  so  unsafe,  to  report  the  same  to  the  local 
inspectors  immediately  upon  the  arrival  of  the  vessel  at  the  first  port 
reached  subsequent  to  the  accident,  or  after  the  discovery  of  such 
unsafe  condition  by  said  engineer. 

Whenever  a  steamer  meets  with  an  accident  involving  loss  of 
life  or  damage  to  property,  it  shall  be  the  duty  of  the  licensed 
officers  of  any  such  steamer  to  report  the  same  in  writing  and  in 
person  without  delay  to  the  nearest  board:  Provided,  That  when 
from  distance  it  may  be  inconvenient  to  report  in  person  it  may 
be  done  in  writing  only  and  the  report  sworn  to  before  any  person 
authorized  to  administer  oaths. 

No  person  shall  receive  an  original  license  as  engineer  or  assist- 
ant engineer  (except  for  special  license  on  small  pleasure  steamers 
and  ferryboats  of  10  tons  and  under,  sawmill  boats,  pile  drivers, 
boats  exclusively  engaged  as  fishing  boats  and  other  similar  small 
vessels)  who  has  not  served  at  least  three  years  in  the  engineer's 
department  of  a  steam  vessel,  a  portion  of  which  experience  must 
have  been  obtained  within  the  three  years  next  preceding  the 
application. 

Provided,  That  any  person  who  has  served  three  years  as  ap- 
prentice to  the  machinist  trade  in  a  marine,  stationary,  or  locomotive 
engine  works,  and  any  person  who  has  served  for  a  period  of  not 
less  than  three  years  as  a  locomotive  or  stationary  engineer,  and 
any.  person  graduated  as  a  mechanical  engineer  from  a  duly  recog- 
nized school  of  technology,  may  be  licensed  to  serve  as  an  engineer 
of  steam  vessels  after  having  had  not  less  than  one  year's  experi- 
ence in  the  engine  department  of  steam  vessels,  a  portion  of  which 
experience  must  have  been  obtained  within  the  three  years  preced- 
ing his  application ;  which  fact  must  be  verified  by  the  certificate,  in 
writing,  of  the  licensed  engineer  or  master  under  whom  the  appli- 
cant has  served,  said  certificate  to  be  filed  with  the  application  of 
the  candidate;  and  no  person  shall  receive  license  as  above,  except 
for  special  license,  who  is  not  able  to  determine  the  weight  necessary 
to  be  placed  on  the  lever  of  a  safety  valve  (the  diameter  of  valve, 
length  of  lever,  distance  from  center  of  valve  to  fulcrum,  weight 
of  lever  and  weight  of  valve  and  stem  being  known)  to  with- 


212  THE  BOILER. 

stand  any  given  pressure  of  steam  in  a  boiler,  or  who  is  not 
able  to  figure  and  determine  the  strain  brought  on  the  braces  of  a 
boiler  with  a  given  pressure  of  steam,  the  position  and  distance  apart 
of  braces  being  known,  such  knowledge  to  be  determined  by  an 
examination  in  writing,  and  the  report  of  examination  filed  with  the 
application  in  the  office  of  the  local  inspectors,  and  no  engineer  or 
assistant  engineer  now  holding  a  license  shall  have  the  grade  of  the 
same  raised  without  possessing  the  above  qualifications.  No  origi- 
nal license  shall  be  granted  any  engineer  or  assistant  engineer  who 
can  not  read  and  write  and  does  not  understand  the  plain  rules  of 
arithmetic. 

Any  person  may  be  licensed  as  engineer  (on  Form  2130^) 
[New  Form  880]  on  vessels  propelled  by  gas,  fluid,  naphtha,  or 
electric  motors,  of  15  gross  tons  or  over,  engaged  in  commerce,  if 
in  the  judgment  of  the  inspectors,  after  due  examination  in  writing, 
he  be  found  duly  qualified  to  take  charge  of  the  machinery  of 
vessels  so  propelled. 

Any  person  holding  a  license  as  engineer  of  steam  vessels,  de- 
siring to  act  as  engineer  of  motor  vessels,  must  appear  before  a 
board  of  local  inspectors  for  examination  as  to  his  knowledge  of 
the  machinery  of  such  motor  vessels,  and  if  found  qualified  shall 
be  licensed  as  engineer  of  motor  vessels.  Form  878,  special  license 
to  engineers,  shall  be  issued  only  to  engineers  in  charge  of  vessels 
of  10  tons  and  under.  All  other  licenses  to  engineers  shall  be 
issued  on  Forms  876  and  877,  according  to  grades  specified  in  this 
section. 

INSPECTING  BOILERS. 

The  necessity  of  care  in  inspecting  steam  boilers  is  apparent 
when  the  amount  of  power  stored  up  while  the  boiler  is  in  commis- 
sion is  known — as  an  illustration:  a  common  sized  boiler  60"  X 
16'  has  38923square  inches,  and  carrying  a  pressure  of  100  pounds, 
has  1946  tons  of  energy.  With  strains  of  expansion  and  contrac- 
tion not  equal  all  over  but  varying,  and  limits  to  the  extreme  — 
(i.  e.)  the  temperature  of  fire  in  furnace  to  that  of  parts  furthest 
from  it,  and  furthermore  when  considering  that  85%  of  the  boiler 
is  concealed — this  by  design  or  principle  of  installation  —  the 


TESTS  AND  INSPECTION.  213 

necessity  of  vigilance  can  be  realized,  especially  when  the  causes  of 
failure  and  defects  are  numerous,  viz. : 

Material, 

Design, 

Construction, 

Appliances, 

Fuel, 

Feed  Water, 

Settings,  and 

Management  and  Care. 

The  hydrostatic  test  is  a  method  not  very  satisfactory  but  often 
necessary  when  access  to  parts  is  impossible,  or  where  a  design 
of  boiler  has  flat  surface  and  notice  of  bulging  or  elongation  must 
be  noted  before  and  after  pressure ;  it  is  necessary  when  notes  of 
bracing  are  to  be  taken  and  when  there  are  any  minor  defects  such 
as  leaks  at  rivets  or  caulking  so  they  can  be  remedied  before  more 
serious  results  follow.  When  a  hydrostatic  test  is  made  of  boilers 
that  are  accessible,  braces  and  such  joints  that  are  weaker  than  the 
original  plates'  tensile  strength,  must  be  inspected  carefully  for  any 
distortions  or  leaks  due  to  riveting,  welds  or  defective  flanges — and 
hidden  defects  may  give  evidence  of  their  presence. 

INSPECTIONS. 

There  are  internal  and  external  inspections,  both  essential  in 
determining  the  boiler's  safety;  for  to  determine  the  safe  working 
pressures,  an  internal  inspection  is  absolutely  necessary. 

The  conditions  for  this  latter  examination  are  as  follows :  The 
boiler  must  be  cool,  water  out  (this  is  supposing  the  boiler  has  been 
in  commission),  ashes  and  soot  removed,  the  mud  only  washed  out  of 
boiler  (it  is  well  to  avoid  excessive  pump  pressure  when  washing 
out  until  inspection  is  made),  this  so  as  not  to  destroy  or  wash  off 
any  evidence  of  leaks  that  might  be  at  points  inaccessible  to  view 
from  the  outside,  but  would  be  in  evidence  at  a  point  inside,  for 
deposits  or  precipitation  in  suspension  would  collect  at  point  where 
leakage  was,  thus  giving  evidence  of  leaks  that  could  not  be  seen 
from  outside ;  this,  of  course,  applies  to  boilers  of  size  and  design 
accessible.  A  thorough  examination  must  be  made  of  all  parts  of 
boiler  accessible ;  sounding  plates  where  possible  over  fire  or  in 


214  THE  BOILER. 

furnace ;  and  parts  where  not  possible  over  fire  or  in  furnace  to  see 
or  sound,  symptoms  that  would  deceive  the  eye,  can,  at  times,  be 
detected  by  the  sense  of  touch;  flanges  and  junction  of  pipes  at 
boilers  must  be  examined,  for  threads  are  an  initial  fracture,  and  by 
the  pipe  or  boiler  expanding  much  undue  strain  results  and  often 
causes  breaking  off  of  pipe.  The  tubes  at  rear  and  front  heads 
being  thin,  are  often  a  source  of  annoyance ;  examine  seams  and 
rivets  for  leakage  and  cracks;  see  that  openings  to  outlets  are  free 
from  obstructions ;  sound  braces ;  examine  flanges,  seams  and  rivets 
internally,  the  condition  as  to  incrustation,  corrosion,  pitting,  and 
when  in  doubt,  give  a  hydrostatic  test;  this  would  reveal  any  weak- 
ness and  leaks  impossible  to  see,  or  defects  developed  by  closing 
down  the  boiler,  resulting  in  contraction.  An  inspection  and  sound- 
ing of  braces  should  follow  the  hydrostatic  test.  Stay  bolts  must  be 
sounded  when  type  of  boiler  is  braced  by  them. 

The  first  thing,  look  at  or  for  the  water  level,  then  the  steam 
pressure;  view  the  furnace,  tube  sheets,  crown  sheets  and  sides  in 
internal  fired  boilers  and  bottom  and  furnace  walls  in  external  fired 
boilers,  looking  at  back  head  from  rear  doors  for  leakage;  (the 
doors  at  rear  end  were  designed  for  access  to  back  head  and 
to  view  when  the  boilers  were  in  commission)  the  blow-off,  and 
as  much  of  the  bottom  as  possible;  brick  work;  examine  the  blow 
off  pipe;  if  it  is  hot  outside  of  valve  it  is  evidence  of  leakage  at 
valve  (this  unless  some  drips  or  other  steam  outlets  are  connected 
into  same  blow-off  pipe).  A  leaky  blow-off  valve  is  a  source  of 
danger,  waste  of  fuel  and  energy;  the  danger  lies  in  the  fact  that 
the  precipitates  will  collect  at  a  point  where  there  is  leakage  and 
as  the  blow-off  pipe  part  of  it  is  exposed  to  heat  one  can  realize 
there  is  danger  by  burning  of  blow-off  pipe. 

The  outside  of  brick  settings  should  be  examined  for  fissures 
or  cracks  caused  by  expanding  of  boiler  and  excessive  heat.  These 
cracks  admit  cold  air,  quantity  governed  by  size  and  draft.  These 
are  the  cause  of  much  loss  of  energy,  certainly  a  waste  of  fuel, 
and  at  expense  of  life  or  boiler. 

Examine  the  feed  appliances ;  test  the  steam  gauge ;  following 
this  up  by  firing  up  of  boiler  to  point  of  safe  working  pressure,  then 
the  setting  of  valve  if  necessary.  When  the  steam  gauge  is  taken  off. 
blow  out  the  pipe  and  be  sure  it  is  clear,  for  oftentimes  these  pipes 


TESTS  AND  INSPECTION.  215 

are  neglected,  and  if  there  is  a  syphon  or  trap  for  condensation,  this 
latter  will  generate  corrosion  and  liable  to  stop  up  stop-cock,  if  nol; 
the  pipe. 

Management  and  care  must  be  considered,  as  we  have  measured 
the  safe  working  pressure  by  design,  material  and  construction. 
The  best  of  man's  work  would  be  trivial  in  th^  hands  of  an 
ignorant  boiler  attendant,  and  the  only  factor  for  safety  in  such 
cases  would  be  to  keep  the  boilers  cold.  Again,  the  inspector  must 
bear  in  mind  that  those  in  power  to  hire  attendants  are  oftentimes 
those  whose  knowledge  of  the  requirements  necessary,  for  men  and 
duties  is  very  limited. 

Fuel  should  be  considered  by  the  inspector,  for  in  these  days  of 
coal  as  fuel  it  must  be  remembered  that  the  more  sulphur  in  the 
fuel,  the  quicker  crystallization  will  develop  in  the  plates. 

Quality  of  feed  water,  its  temperature  and  point  of  admission 
should  be  looked  after;  for  these  are  elements  that  will,  in  a  meas- 
ure, give  evidence  of  what  one  expects. 

POINTS  TO  CONSIDER  WHEN   INSPECTING  BOILERS. 

Evidence  of  excessive  firing;  piping  of  boilers  for  best  effect  to 
allow  for  expansion;  avoid  rigidity;  pipe  of  sufficient  strength  for 
high  pressures;  deterioration  from  leakage;  corrosion  from  sul- 
phuric action — soot  and  moisture  develops  sulphuric  acid.  Remember 
that  75  per  cent  of  the  boiler  is  concealed  either  by  the  design  or  set- 
tings and  much  depends  on  viewing  and  examining  the  minimum  por- 
tion ;  that  a  large  amount  of  energy  is  stored  up  in  the  boiler  when 
in  commission ;  for  instance,  a  boiler  60"  X  16'  at  100  pounds 
pressure  has  approximately  1946"  tons  of  energy  stored  in  it.  This 
suggests  reasons  for  thought.  There  is  lamination  or  blisters  and 
bagging  of  plates  to  look  for,  or  to  be  expected.  See  that  water 
columns  are  properly  connected  and  convenient  to  try  at  all  times; 
that  the  safety  valve  is  of  sufficient  size  and  operative ;  that  blow- 
pipes are  of  proper  size  and  protected ;  that  the  feed  water  ap- 
pliances are  ample  and  more  than  one  to  feed  boiler ;  that  the 
feed  water  enters  at  a  suitable  place ;  that  the  check  and  stop  valves 
are  connected  and  placed  a  reasonable  distance  from  boiler ;  that  the 
boiler  (if  externally  fired)  is  properly  set  for  heat  distribution; 
that  the  grates  are  not  too  close  to  the  boiler  (bottom),  for  space 
is  necessary  for  combustion  and  conductivity  of  heat.  Do  not  for- 


216  THE  BOILER. 

get  that  it  is  a  human  being  who  is  in  charge  of  the  boiler  and 
that  it  is  human  to  err.  This  will  impress  the  inspector  that  if 
the  man  in -charge  knew  as  much  as  he  does,  the  inspector's  services 
would  not  be  necessary.  It  also  qualifies  the  old  adage,  "No  man 
is  the  best  judge  of  his  own  work  or  actions." 

%     THE    SAFE    WORKING    PRESSURE. 

Years  ago  the  Lloyds  of  Europe  adopted  a  rule  to  govern  the 
safe  working  by  pressure,  viz. :  One  sixth  of  the  tensile  strength 
of  plate,  multiplied  by  thickness  of  the  plate,  and  divided  by  the 
radius ;  and  for  years  this  rule  was  used  universally.  It  was  the 
supposition  that  the  plate  and  rivet  strength  would  be  near  equal 
and  construction  the  best,  20  per  cent  was  added  for  double  riveted 
longitudinal  seam.  At  that  time  low  pressures  were  the  rule,  con- 
sequently security  or  safety  was  reasonably  expected ;  but  when 
other  factors  came  to  be  considered,  different  types  of  engines  that 
required  higher  pressures  and  fuel  became  a  prime  factor,  along 
with  space,  the  demand  for  higher  pressure  became  apparent  and 
something  more  than  the  old  time  design  and  construction  of  boilers 
had  to  be  considered.  The  weakest  point  had  to  be  strengthened, 
necessitating  butt  joints,  drilled  holes,  modern  flanging,  braces  and 
bracing,  larger  plates  and  less  joints,  abandonment  of  cast  iron  for 
man  holes  and  openings.  Boiler  making  tools  and  machinery  had  to 
keep  pace,  thus  the  advancement  made  in  the  craft  necessitates  some 
more  definite  rules  to  govern  us  in  the  allowing  of  a  safe  working 
pressure.  The  factor  of  six,  as  formerly  used,  was,  no  doubt,  little 
enough  when  iron  plates,  short  and  narrow,  were  used ;  chipping 
done  by  hand,  i.  e.,  the  grooving  by  same ;  punched  holes ; 
the  drift  pin  and  designing  of  seams.  Thus  it  was  absolutely 
necessary  for  a  large  factor  of  safety ;  but  as  stated,  boiler  con- 
struction to-day  is  modern  and  complies  to  the  demand  for  high 
pressures.  We  are  too  advanced  to  use  such  a  large  safety 
factor  as  6.  It  is  true  there  are  the  extremes,  but  there  are  things 
that  must  be  considered  in  this  matter  of  safety  factor,  viz.,  design ; 
tensile  strength ;  thickness  of  plate ;  diameter  of  hole ;  diameter  and 
pitch  of  rivet;  shearing  strength  of  rivet;  diameter  of  boiler; 
bracing;  lowest  percentage  of  seam.  It  might  be  carried  further 
to  be  more  definite,  by  considering  the  boiler's  use ;  if  boiler  would 


TESTS  AND  INSPECTION.  217 

be  forced ;  if  loads  would  vary ;  type  of  engine ;  if  the  boiler  would 
be  used  for  power  or  heating  only. 

It  would  not  be  consistent  to  lay  clown  any  specified  rule  to 
govern  all  cases.  It  may  be  that  the  boiler  would  deteriorate  faster 
in  one  location  than  another.  This,  of  course,  would  be  a  local 
consideration,  but  in  these  days  of  modern  ideas,  designs  and  con- 
struction, a  factor  of  four  would  be  ample  to  cover  all  differences  in 
construction  and  material. 

Prepare  for  inspection  by  having  ashes  and  deposits  removed 
from  under  boiler  and  ash  pits,  tubes  cleaned  and  soot  removed. 

Allow  boiler  and  setting  time  to  cool  off  gradually,  open  gauge- 
cocks  before  letting  water  run  out.  Leave  dampers  open  and 
furnace  door  closed. 

Wash  boiler  out  and  have  same  as  dry  as  possible. 

Take  steam  gauges  down   for  testing. 

Steam  gauges  should  be  connected  with  a  union  between  stop 
cock  and  gauge,  so  that  the  latter  can  be  taken  off  syphon  or  pipe 
without  disturbing  threads  that  would  alter  position  when  connect- 
ing gauge  again.  It  is  advisable,  when  having  gauges  tested,  to 
raise  steam  and  note  point  of  blowing  off,  and  adjust  safety  valve 
if  necessary. 

If  a  hydrostatic  test  is  to  be  made  have  pump  and  piping  con- 
nected and  the  hydrostatic  test  applied  to  a  pressure  equal  to  the 
proportions  of  150  pounds  to  100  pounds  working  pressure. 

The  U.  S.  Government  makes  annual  inspections  and  tests  and 
all  mandates  are  carried  out  to  the  letter. 

Testing  of  plates,  piping  and  material  must  fill  all  requirements, 
or  condemnation  or  rejection  follows.  Boilers  and  appliances  must 
be  approved  before  installing  and  put  into  commission. 

Some  of  the  requirements  are  as  follows : 

CAST  STEEL  AND  CAST  IRON. 

No  cast  steel  or  cast  iron  subject  to  pressure  shall  be  allowed 
to  be  used  4n  boilers  or  the  pipes  connected  thereto,  except  as  de- 
scribed as  follows: 

Cast  iron  or  cast  steel  may  be  used  in  the  construction  of  man- 
hole and  hand-hole  plates,  valves  and  cocks,  water  columns,  flanges, 
saddles,  ells,  tees,  crosses  or  manifolds  when  such  flanges,  saddles, 


218  THE  BOILER. 

ells,  tees,  crosses,  valves  and  cocks,  or  manifolds  are  bolted  or 
riveted  directly  to  the  boiler  and  the  valves  or  cocks ;  also,  casings 
of  slip  joints  in  pipes :  Provided,  however,  that  the  material  shall 
be  of  the  best  grade  and  of  suitable  thickness  and  uniform  section 
for  the  pressure  allowed  on  boilers. 

FEED     WATER. 

The  feed  water  shall  not  be  admitted  into  any  boiler  at  a  temper- 
ature less  than  100°  F.,  and  no  marine  boiler  shall  be  used  with- 
out having  proper  auxiliary  appliances  for  supplying  said  boilers 
with  water  in  addition  to  the  usual  mode  employed. 

NAME     PLATES. 

There  shall  be  fastened  to  each  boiler  a  plate  containing  the 
name  of  the  manufacturer  of  the  material,  the  place  where  manu- 
factured, the  tensile  strength,  the  name  of  the  builder  of  the  boiler, 
when  and  where  built. 

FUSIBLE    PLUGS. 

Every  boiler,  other  than  boilers  of  the  water-tube  type,  shall 
have  at  least  one  fusible  plug  as  described  below.  Plugs  shall  be 
made  of  a  bronze  casing  filled  with  good  Banca  tin  from  end  to 
end.  The  manufacturers  of  fusible  plugs  shall  stamp  their  name 
or  initials  thereon  for  identification  and  shall  file  with  the  local  in- 
spectors a  certificate,  duly  sworn  to,  that  such  plugs  are  filled  with 
Banca  tin. 

Fusible  plugs,  except  as  otherwise  provided,  shall  have  an  ex- 
ternal diameter  of  not  less  than  three-fourths  of  an  inch  pipe  tap, 
and  the  Banca  tin  shall  be  at  least  one-half  of  an  inch  in  diameter 
at  the  smallest  end  and  shall  have  a  larger  diameter  at  the  center 
or  at  the  opposite  end  of  the  plug. 

Fusible  plugs,  when  used  in  the  tubes  of  upright  boilers,  shall 
have  an  external  diameter  of  not  less  than  three-eighths  of 
an  inch  pipe  tap,  and  the  Banca  tin  shall  be  at  least  one- fourth  of 
an  inch  in  diameter  at  the  smaller  end  and  shall  have  a  greater 
diameter  at  the  opposite  end  of  the  plug:  Provided,  however,  that 
all  plugs  used  in  boilers  carrying  a  steam  pressure  exceeding  150 
pounds  to  the  square  inch  may  be  reduced  at  the  smaller  end  of 
the  Banca  tin  to  five-sixteenths  of  an  inch  in  diameter. 

Externally  heated  cylindrical  boilers,  with  flues,  shall  have  one 


TESTS  AND  INSPECTION.  219 

plug  inserted  in  one  flue  and  also  one  plug  inserted  in  shell  of 
each  boiler,  immediately  below  the'  fire  line  and  not  less  than  4 
feet  from  the  front  end :  Provided,  however,  that  when  such 
flues  are  not  more  than  6  inches  in  diameter  a  fusible  plug  of  not 
less  diameter  than  three-eighths-inch  pipe  tap  may  be  used  in  such 
flues. 

Other  shell  boilers,  except  especially  provided  for,  shall  have 
one  plug  inserted  in  the  crown  sheet  of  the  back  connection. 

Vertical  tubular  boilers  shall  have  one  plug  inserted  in  one 
of  the  tubes  at  least  2  inches  below  the  lowest  gauge  cock,  but 
in  boilers  having  a  cone  top  the  plug  shall  be  inserted  in  the  upper 
tube  sheet. 

All  plugs  shall  be  inserted  so  that  the  small  end  of  the  Banca 
tin  shall  be  exposed  to  the  fire. 

It  shall  be  the  duty  of  the  inspector  at  each  annual  inspection 
to  see  that  the  plugs  are  in  good  condition. 

GAUGE    COCKS    AND    WATER    GLASS. 

All  boilers  shall  be  supplied  with  one  reliable  water  gauge  and 
three  gauge  cocks  in  each  boiler:  Provided,  that  when  the  gauge 
glass  and  gauge  cocks  are  connected  to  the  boilers  by  a  water 
column  there  must  be  an  additional  gauge  cock  inserted  in  the 
head  or  shell  of  boiler.  The  lower  gauge  cock  in  boilers  more 
than  48  inches  in  diameter  shall  not  be  less  than  4  inches  from 
the  top  of  the  flues  or  tubes.  In  boilers  less  than  48  inches  in 
diameter  the  lower  gauge  cock  shall  not  be  less  than  2y2  inches 
above  the  top  of  the  flues  or  tubes.  A  gauge  glass  shall  be  con- 
sidered a  reliable  water  gauge,  and  a  float  such  as  used  on  western 
river  steamers  shall  be  considered  on  such  boilers  as  a  reliable 
water  gauge. 

In  vertical  boilers  or  boilers  of  the  water-tube  type  the  location 
of  the  lowest  gauge  cock  shall  be  determined  by  the  local  inspectors. 

Boilers  known  as  flash  boilers  constructed  of  a  continuous  coil 
of  pipe  or  series  of  coils  of  pipes  under  three-fourths  inch  in  diam- 
eter, whose  construction  has  been  approved  by  the  Board  of  Super- 
vising Inspectors,  shall  not  be  required  to  be  supplied  with  gauge 
cocks  or  low- water  gauges. 


220  THE  BOILER. 

DRILLING    TO    DETERMINE    THICKNESS. 

Any  boiler  ten  years  old  or  more  shall,  at  the  first  annual 
inspection  thereafter,  be  drilled  at  points  near  the  water  line  and 
at  bottom  of  shell  of  boiler,  or  such  other  points  as  the  local  in- 
spectors may  direct,  to  determine  the  thickness  of  such  material 
at  those  points ;  and  the  steam  pressures  allowed  shall  be  gov- 
erned by  such  ascertained  thickness  and  the  general  condition  of 
the  boiler. 

HYDROSTATIC    PRESSURE. 

The  hydrostatic  pressure  applied  must  be  in  the  proportion 
of  150  pounds  to  the  square  inch  to  100  pounds  to  the  square  inch 
of  the  steam  pressure  allowed  and  the  inspector,  after  applying 
the  hydrostatic  test,  must  thoroughly  examine  every  part  of  the 
boiler. 

In  applying  the  hydrostatic  test  to  boilers  with  a  steam  chimney, 
the  test  gauge  should  be  applied  to  the  water  line  of  such  boilers. 

All  coil  and  pipe  boilers  hereafter  made,  when  such  boiler  is 
completed  and  ready  for  inspection,  must  be  subjected  at  the  first 
inspection  to  a  hydrostatic  pressure  double  that  of  the  steam  pres- 
sure allowed  in  the  certificate  of  inspection. 

The  use  of  malleable-iron  or  cast-steel  manifolds,  tees,  return 
bends  or  elbows  in  the  construction  of  pipe  generators  shall  be 
allowed  and  the  pressure  of  steam  shall  not  be  restricted  to  less 
than  one-half  the  hydrostatic  pressure  applied  to  pipe  generators 
unless  a  weakness  should  develop  under  such  test  as  would  render 
it  unsafe  in  the  judgment  of  the  inspector  making  such  inspection. 

DRUMS  AND   HEADS. 

All  drums  attached  to  coil,  pipe,  sectional  or  water-tube  boilers 
not  already  in  use  or  actually  contracted  for,  to  be  built  for  use 
on  a  steam  vessel  and  its  building  commenced  at  or  before  the 
date  of  the  approval  of  this  rule,  shall  be  required  to  have  the 
heads  of  wrought  iron  or  steel  or  cast  steel  flanged  and  substan- 
tially riveted  to  the  drums  or  secured  by  bolts  and  nuts  of  equal 
strength  with  rivets,  in  all  cases  where  the  diameters  of  such  drums 
exceed  6  inches. 

Drums  and  water  cylinders  constructed  with  a  bumped  head 
at  each  or  either  end,  (any  opening  in  the  shell  or  heads  to  be 


TESTS  AND  INSPECTION.  221 

reinforced  as  required  by  the  rules  of  the  Board,  the  circumferen- 
tial and  horizontal  seams  to  be  welded  and  properly  annealed 
after  such  welding  is  completed),  when  tested  with  a  hydrostatic 
pressure  at  least  double  the  amount  of  the  steam  pressure  allowed 
may  be  used  for  marine  purposes. 

PIPES. 

COPPER. 

All  copper  pipe  subject  to  pressure  shall  be  flanged  over  or 
outward  to  a  depth  of  not  less  than  twice  the  thickness  of  the 
material  in  the  pipe  and  such  flanging  shall  be  made  to  a  radius 
not  to  exceed  the  thickness  of  the  pipe.  On  boilers  whose  con- 
struction was  commenced  after  June  30,  1905,  no  bend  will  be 
allowed  in  copper  pipe  of  which  the  radius  is  less  than  one  and 
one-half  times  the  diameter  of  the  pipe  and  such  pipe  must  be 
so  led  and  flanges  so  placed  that  they  may  be  readily  taken  down  if 
required.  Such  pipes  must  be  protected  by  iron  casings  when  run 
through  coal  bunkers  and  must  be  clear  of  the  coal  chutes. 

The  flanges  of  all  copper  steam  pipes  over  3  inches  in  diam- 
eter shall  be  made  of  brass  or  bronze  composition,  forged  iron  or 
steel,  or  open-hearth  steel  castings  and  shall  be  securely  brazed  or 
riveted  to  the  pipe :  Provided,  however,  that  when  such  pipes  are 
properly  formed  with  a  taper  through  the  flange,  such  taper  being 
fully  reinforced,  the  riveting  or  brazing  may  be  dispensed  with : 
And  provided,  also,  that  when  the  pipe  has  been  expanded  by 
proper  and  capable  machinery  into  grooved  flanges  and  the  pipe 
flared  out  at  the  ends  to  an  angle  of  approximately  20°,  said  angle 
to  be  taken  in  the  direction  of  the  length  of  the  pipe  and  having 
a  depth  of  flare  equal  to  at  least  one  and  one-half  times  the  thick- 
ness of  the  material  in  the  pipe,  said  riveting  or  brazing  may  be 
dispensed  with.  Where  copper  pipes  are  expanded  into  or  riveted 
to4  flanges  it  will  be  necessary  for  the  pipes  with  their  flanges  at- 
tached to  withstand  a  hydrostatic  pressure  of  two  and  one-half 
times  the  boiler  pressure. 

Flanges  must  be  of  sufficient  thickness  and  must  be  fitted  with 
such  number  of  good  and  substantial  bolts  to  make  the  joints  at 
least  equal  in  strength  to  all  other  parts  of  the  pipe. 

Any  form  of  joint  that  will  add  to  the  safety  or  increase  the 


222  THE  BOILER. 

strength  of  flange  and  pipe  connections  over  those  provided   for 
by  this  rule,  will  be  allowed  on  any  and  all  classes  of  steam  pipe. 

WATER    TUBE    AND    COIL    BOILERS. 

Blue  prints  or  drawings  of  coil  boilers  and  of  other  boilers,  with 
their  specifications,  submitted  to  the  Board  of  Supervising  In- 
spectors for  approval  under  section  4429,  Revised  Statutes  of  the 
United  States,  must  be  in  duplicate  before  action  thereon  will  be 
taken  by  the  Board,  with  a  view  of  approving  the  same ;  one  set 
to  be  filed  with  the  records  of  the  Board  of  Supervising  Inspectors 
and  the  other  with  the  records  of  the  supervising  inspector  of  the 
district  where  the  manufacturer  of  the  boiler  is  located. 

Rule  to  find  the  working  pressure  allowable  on  cylindrical  shells 
of  water  tube  or  coil  boilers,  when  such  shells  have  a  row  or  rows  of 
pipes  or  tubes  inserted  therein :  From  pitch  of  holes  subtract  diame- 
ter of  pipe,  then  multiply  by  thickness  of  plate  and  one-sixth  of 
tensile  strength.  Divide  this  product  by  pitch  of  holes  multiplied  by 
radius. 


FORMULA: 
p— d XT X  1/6  of  TS 


pXR 
LEGEND: 


=  pressure 


p=  pitch  =1" 
d  =  diameter  of  pipe  =  1" 
T  =  thickness  of  plate  =  K?" 
TS=  tensile  strength  =60000 
R  =  radius  =  10" 


EXAMPLE: 

2  =  pitch 

1  =  diameter  of  pipe 

1 

.  5  =  thickness  of  plate 

pitch  =   2"    .5 
radius  =10"     10000  =  one-sixth  of  tensile  strength  of 

plate 

20)      5000 .  0  (250  pounds  pressure  allowed 
40 

100 
100 


CHAPTER  X. 


FEED  WATER   HEATING  AND   PURIFICATION. 

While  boiler  designing,  construction  and  setting  have  received 
the  thought  and  attention  of  many  prominent  specialists  of  this 
age,  this  for  security  against  the  high  pressures  necessary  to  meet 
the  demands  of  modern  engines  and  that  factor,  fuel,  it  is  apparent 
even  to  the  layman  that  the  feed  water  for  steam  boilers  must  be 
a  factor  worthy  of  much  consideration,  for  it  means  life  of  boiler 
and  efficiency  of  same  —  this  under  varying  conditions  even  to  those 
who  have  free  fuel  and  best  of  water.  Various  appliances  and 
methods  are  employed  to  obtain  the  best  possible  results  from  feed 
water,  for  the  latter  is  one  of  the  primaries  for  disaster  and  expense 
in  operation.  Many  well  designed  and  well  constructed  boilers 
have  been  condemned  on  this  account.  Reputations  that  have  been 
built  on  years  of  experience  and  study  have  been  affected  by  local 
influences  —  bad  feed  water. 

Instances  can  be  cited  where  boilers  designed  and  made  by  the 
most  progressive  boiler  makers  have  been  condemned  and  only 
material  and  construction  given  by  the  operators  as  a  cause  for 
failures  or  reduced  condition.  Feed  water  is  the  initial  factor  in 
the  steam  plant.  To  install  the  best  designed  and  constructed  boiler 
from  the  best  of  material  and  subject  the  same  to  bad  feed  water, 
failure  of  seams  or  plate  are  the  results  expected. 

In  some  localities  incrustation  and  deposits  from  water  are  un- 
known — •  this  where  matter  which  is  soluble  in  land  strata  are 
absent  —  but  these  locations  are  very  few  to  the  major  part  of  this 
country.  Hence  the  necessity  for  an  appliance  —  a  vital  adjunct 
to  the  steam  plant  —  i.  e.,  a  feed  water  purifier. 

Many  and  varied  are  the  appliances  now  used  for  this  purpose ; 
it  would  seem  that  each  one  has  its  advocates  and  no  doubt  its 
niche,  or  suitable  place.  They  all  aim  to  obtain  the  best  possible 
results,  but  many  fail  to  accomplish  the  maximum  effect. 

223 


224  THE  BOILER. 

A  brief  description  of  types  mostly  in  use  may  be  interesting 
or  at  least  give  some  food  for  thought.  Possibly  future  discussions 
may  change  views  and  show  that  present  convictions  are  wrong. 
Such  subjects  are  almost  inexhaustible  and  when  analyzed  they  can 
be  made  subjects  of  much  merit  and  of  great  interest  to  those  whose 
lives  are  devoted  to  steam  engineering.  For  instance,  analyzing  the 
boiler,  we.  find : 

Material. 

Design. 

Construction. 

Settings. 

Appliances. 

Management  and  care,  and 

Feed  water.    . 

It  is  the  latter  which  I  will  attempt  to  digest,  not  in  material 
value  order,  or  on  personal  judgment,  but  as  they  suggest  themselves 
to  the  mind  when  reviewing  this  subject.  A  brief  description  of 
types  in  use  are : 

1.  Auxiliary  pipes. 

2.  Water  backs. 

3.  Pipes  in  uptakes. 

4.  Closed  heaters. 

5.  Boxes  or  receptacles  in  boilers. 

6.  Live  steam  heaters. 

7.  Open  heaters. 

There  is  no  question  but  that  any  or  all  of  these  types  have 
some  merit  in  some  particular  place  or  under  some  conditions. 

I  will  take  them  up  in  individual  order  and  try  to  point  out  their 
degree  of  usefulness,  or  advantages,  one  over  the  other. 

In  order  to  obtain  the  best  values,  we  must  look  for  require- 
ments, they  must  be  known ;  then  put  them  in  valued  order. 

The  heater  and  purifier  must  have  some  of  these  requirements. 
There  is  much  variance  with  each  type,  no  two  alike,  when  units  of 
measurement  are  taken.  Quotations  of  prices  are  based  on  indi- 
vidual units  of  measurement  and,  like  the  different  types  of  boilers, 
are  rated  on  a  given  quantity  of  heating  surface  ranging  from  6  to 
15  square  feet — this  irrespective  of  plate  thickness,  grate  surface, 
fuel  or  draft.  It  is  the  same  with  the  heaters  and  so-called  purifiers. 


MISCELLANEOUS.  225 

1.    AUXILIARY    PIPES. 

These  are  connected  to  boiler,  water  and  steam  connections. 
They  simply  make  additional  heating  surface  and  have  very  little 
merit  otherwise.  They  are  not  to  be  recommended  for  either  effi- 
ciency, safety  or  economy.  They  are  short-lived,  a  menace  to  se- 
curity, subject  to  incrustation  and  fracture  due  to  expansion  and 
contraction;  impossible  to  clean,  making,  oftentimes,  long  and 
serious  delays.  It  is  like  courting  disaster  to  apply  these  to  a 
boiler. 

2.    WATER   BACKS. 

These  are  usually  placed  back  of  boiler,  top  of  setting,  or  in 
front  of  or  at  sides  of  furnace  and  shapes  are  either  cylindrical  or 
flat.  They  are  supposed  to  act  in  a  dual  capacity  —  feed  water 
heater  and  form  an  arch  or  a  part  of  the  furnace.  It  cannot  be 
said  that  there  is  any  fuel  economy.  They  are  a  part  of  the  boiler 
and  absorb  furnace  heat.  They  have  boiler  pressure,  and  are  no 
prevention  against  solids  in  suspension  going  into  boiler.  They 
often  become  incrustated,  necessitating  repairs,  and  when  one  con- 
siders the  difference  in  temperature  in  such  a  short  space,  between 
parts  exposed  to  fire  and  boiler  room,  expectations  can  be  realized. 
The  tempering  of  water  by  heat  before  going  to  boiler,  as  in  case 
of  injectors,  is  the  only  point  of  merit  they  have.  The  cylinder 
type  may  have  some  advantages  —  strength  of  form  and  being  more 
accessible  to  clean.  The  flat  type  offers  little  in  that  respect.  The 
latter  are  more  costly,  owing  to  the  flange  and  the  bracing  by  stay 
bolts.  Again,  either  type  has  the  disadvantage  of  adding  weight 
on  settings  or  walls.  The  latter  are  expensive  items  in  keeping  up 
the  boiler  plant. 

3.    PIPES  IN  UPTAKE. 

This  application  for  heating  feed  water  has  sometimes  primary 
benefits  in  the  way  of  economy,  due  to  absorbing  heat  from  escaping 
gases.  But  this  is  largely  a  guess  and  it  is  a  question  if  they  are 
often  or  long  economical,  for  the  heat  escaping  up  the  stack  or 
uptake  is  a  large  factor,  in  fact  very  necessary  and  essential  when 
natural  draft  is  depended  on,  and  supply  limited ;  for  to  reduce  this 
temperature  means  less  oxygen  to  fuel. 


226  THE  BOILER. 

In  some  places,  and  under  some  conditions,  there  may  be  some 
economy,  but  in  the  average  plant,  none.  Incrustated  pipes,  solids 
in  suspension  forced  into  boilers,  fractures,  delays  in  removal  or 
cleaning,  can  be  expected.  This  type  cannot  be  considered  a  profit- 
able investment  even  in  plants  where  induced  draft  is  used,  unless 
water  is  purified  before  going  through  same. 

4.    CLOSED    HEATERS. 

Water  or  steam  tubes  or  pipes,  return  bends,  corrugated  or 
straight,  coils,  with  and  without  setting  chambers. 

These  appliances  are  made  in  varying  forms,  the  aim  being  to 
obtain  heat  from  exhaust  steam  in  non-condensing  plants,  but  it  is 
futile  to  expect  anything  like  purification  of  feed  water  from  this 
type.  No  matter  what  design  they  are,  their  value  is  limited  to  that 
of  heating  to  some  extent,  the  feed  water  then  at  a  low  temperature. 
They  have  pressure  in  excess  of  the  boiler,  this  owing  to  the  neces- 
sity of  lifting  check  valve  or  overcoming  weight  of  water  and  pres- 
sure in  boiler.  The  exhaust  steam  temperature  must  be.  conducted 
through  plate  pipes,  coils  or  tubes,  there  being  no  chance  for  precipi- 
tation other  than  light  solids,  such  as  magnesia — this  owing  to  lack  of 
temperature  imparted  by  exhaust  and  the  existing  pressure  in  heater, 
even  with  back  pressure  on  engine,  for  to  precipitate  other  solids 
the  temperature  must  be  increased  with  pressure  obtained  in  heater. 
For  instance,  if  pressure  was  100  pounds,  the  temperature  necessary 
would  be  338  F.,  but  at  atmospheric  pressure  it  would  be  212  F. 
Then  what  chances  could  there  be  even  with  back  pressure  when 
the  heat  must  be  conducted  through  plate?  Should  light  solids  be 
precipitated  these  would  be  forced  into  boiler.  Again,  this  type  or 
class  of  heater  is  hard  if  not  almost  impossible  to  clean.  Thus, 
should  any  solids  be  in  suspension  and  collect,  when  the  attempt  is 
made  to  clean  exhaust  pipes  must  be  disconnected  and  those  of 
water  or  steam  tube  type  are  difficult  for  access. 

Those  with  a  so-called  setting  chamber  have  very  little  effect 
from  settling,  for  these  have  a  continuous  circulation  when  feed 
water  passes  through.  Hence  settling  is  impossible  when  pumps 
would  be  stopped ;  then  the  only  amount  of  settling  would  be  equal 
to  that  which  volume  of  water  at  that  time  would  hold. 

One  argument  used  in  its  favor,  as  heard,  is  that  "only  one 


MISCELLANEOUS.  227 

pump  is  required."  This  apparently  is  enough  to  convince  the  lay- 
man that  to  select  this  type  is  wise.  Some  of  these  closed  heaters 
may  have  individual  merit.  For  instance,  the  return  bend  expands 
on  one  end  —  that  is,  it  is  free  to  do  so.  Then  the  corrugated  tube 
has  additional  heating  surface  and  prevents  leaking  at  ends,  expan- 
sion and  contraction  being  taken  up  by  the  corrugations.  But  in 
this  form  of  heater,  condensation  is  usually  lost  with  its  purity  and 
heat  units.  This  heater  is  fast  being  relegated  to  one  place  in  the 
power  plant,  and  that  place  is  the  condensing  one.  Its  position 
being  between  the  engine,  cylinder  and  injection  water.  Its  value, 
besides  giving  some  heat,  is  to  prevent  condensation  of  steam  in 
cylinder  by  the  injection  water. 

5.    THE  BOX  OR  RECEPTACLE  THAT  IS  PLACED  IN  THE  BOILER. 

This  idea  of  a  feed  water  heater  and  purifier  is  not  new.  It 
is  old  and  has  been  tried  and  found  wanting.  These  may  be  ob- 
tained in  any  shape,  or  to  be  put  or  placed  in  any  part  of  boiler, 
on  top  of  tubes  or  under  same.  That  does  not  prevent  results  from 
being  the  same.  Though  feeding  impure  water  into  a  box  having 
holes  or  slots,  it  is  a  fact  the  water  must  find  its  level,  must  flow 
to  that  point  where  steam  globules  are  formed  and  then  ascend 
into  space  to  diffuse.  Precipitation  does  not  occur  at  the  instant 
of  contact  with  heat.  Even  if  it  did  these  receptacles  are  only 
settling  pans  and  the  perforations  are  limited  —  this  to  confine  water 
inside  as  long  as  possible  and  to  aid  precipitation.  Danger  is 
courted,  for  should  those  openings  become  stopped  up  danger  from 
low  water  is  the  result.  If  these  boxes  are  open  then  the  solids 
will  find  their  way  to  all  parts  of  boiler  —  this  through  circulation. 
These  boxes  obstruct  steam  passages,  retard  circulation  and  make 
internal  inspections  impossible.  The  price  involved  in  these  would 
bo  far  better  invested  in  something  to  prevent  solids  from  going  into 
boiler  or  in  aiding  to  purify  feed  water  before  going  into  boilers, 
this  being  done  now  in  modern  plants. 

6.    THE   LIVE   STEAM    HEATER   AND   PURIFIER. 

The  live  steam  purifier,  like  all  other  contrivances  and  appliances 
for  bettering  the  condition  of  boilers  and  increasing  efficiency  and 
reducing  the  hazard  and  risk  in  steam  boilers,  has  its  advocates. 


228  THE  BOILER. 

Much  has  been  claimed  for  it.  Like  preceding  types  it  no  doubt 
has  some  features  that  might  at  least  appear  commendable.  But, 
however,  claims  are  one  thing,  effects,  results  and  investments  are 
others.  The  name  is  somewhat  misleading.  Its  value  ceases  as  an 
investment  when  cost  and  maintenance  are  experienced.  While  ad- 
mitting that  it  would  have  one  factor,  that  of  precipitation  of  solids 
that  were  held  in  solution  by  boiler  pressure  temperature,  this  does 
not  alone  insure  purity  of  water  or  establish  it  as  a  purifier,  for 
two  results  are  necessary  for  purification  of  feed  water  —  viz. : 
precipitation  and  filtering. 

The  pans  used  are  settling  surfaces  for  some  of  the  solids  that 
will  settle,  but  much  goes  into  boiler  through  gravity  circulation. 
The  live  steam  heaters  are  selected  for  only  one  action  —  precipita- 
tion —  and  this  at  the  expense  of  condensation,  they  being  in  a 
position  at  a  considerable  distance  from  water  line  to  grate  surface. 
Some  argue  that  if  only  some  of  the  solids  are  prevented  from  going 
into  boiler,  the  value  of  the  live  steam  heater  must  be  considered 
with  fuel  saving  and  efficiency  gained,  this  offsetting  the  condensa- 
tion. But  there  are  points  of  disadvantages.  The  added  hazard, 
being  subjected  to  the  full  boiler  pressure,  has  additional  energy 
stored  in  it.  They  are  placed  much  higher  than  boiler  water 
line,  access  to  clean  difficult,  involve  much  expense  for  installation, 
special  frame  support  and  floor.  When  points  of  advantages  are 
taken  into  consideration  and  weighed  with  the  disadvantages,  care 
should  be  taken  when  selection  of  a  feed  water  purifier  is  to  be 
made. 

7.    THE  OPEN  HEATER  AND  PURIFIER. 

Feed  water  purification  is  a  possibility  and  this  is  when  open 
type  of  feed  water  heater  and  purifier  is  used,  (this  is  only  when 
care  and  reason  are  exercised  in  selection),  and  this  can  be  done 
with  minimum  loss  of  furnace  heat.  It  is  practically  the  solution 
solved  when  the  elements  and  requirements  are  adjusted  and  propor- 
tions are  .proper,  viz.,  time  and  temperature. 

Where  a  lack  of  temperature  fails  time  must  be  increased. 
Additional  body  of  water  will  represent  time. 

This  appliance  is  open  to  the  atmosphere.  The  feed  water  supply 
comes  in  contact  with  the  exhaust  steam  or  steam  used  for  tern- 


MISCELLANEOUS.  229 

perature  necessary  for  precipitation.  It  will  produce  a  partial 
vacuum  on  engine  when  exhaust  steam  is  used.  Precipitation  occurs 
at  lowest  possible  temperature,  15  to  20  per  cent  of  pure  water  being 
gained  by  condensation.  There  are  some  open  heaters  that  are  so 
constructed  that  precipitation  is  expected  at  instant  of  contact  of 
steam  and  water.  Others  have  so  limited  a  supply  of  water  that  no 
time  for  action  is  allowed.  In  some  cases  a  few  strokes  of  the 
pump  takes  all  the  water  out.  Others,  while  they  have  a  copious 
supply  of  water,  the  filtering  material  is  such  that  it  separates,  thus 
leaving  water  with  its  solids  in  suspension  free  to  go  to  pump,  then 
to  the  boiler.  Others,  again,  have  no  facilities  for  cleaning  the  filter, 
unless  at  expense  of  closing  down  or  putting  cold  water  into  boilers. 
Most  of  these  are  simply  receivers,  heaters  or  condensers.  They 
cannot  be  termed  feed  water  purifiers. 

A  few  suggestions  on  selection  may  be  in  order.  Conditions 
must  be  observed.  First,  quality  of  water  to  be  used ;  this  will  de- 
termine the  filtering^  surface,  but  the  main  requirements  are :  high 
temperature,  large  body  of  water,  large  amount  of  filtering  surface, 
easy  to  clean. 

The  two  elements,  time  and  temperature,  are  necessary. 

Points  to  be  considered  in  selecting  slow  filtering  —  filter  acces- 
sible to  clean  when  in  use,  filtering  material  and  adjustment  of 
same  against  derangement. 

When  filtering  is  operative,  deposits  will  collect  on  filtering  ma- 
terial, thus  the  necessity  of  some  way  fo  clean  off  same  at  any  time. 

There  is  the  greatest  of  economy  in  heating  feed  water  by 
exhaust  steam,  even  when  the  latter  is  used  for  heating  purposes. 
In  this  age  we  are  resorting  to  chemistry  as  a  positive  aid  in  water 
purification. 


230 


THE  BOILER. 


H  ° 

*  g 

J,  1 

S  I 


oo  oo  oo  oo  oo  oo  oo  oo  oo  oo  o*»  o^  ^  o^  ^  ^  ^  o^  ^  ^  ^  o  o 


OO  OO  OO  OO  OO  OO  OO  OO  OO  O^  ^  ^  O^»  O**  O^i  ^  ^  ^  O>  O^i  O  O  O 


10  ro  '—  *  O  ^  t^ 
CO 


IP 

1-1  6*0 

H 


o  o  o  o  o  o  o 

i— I  CO  CO  CO  CO  CO  CO 


o 


T3  y, 


II 

rt   C 


tf>   oJ 

C/3     flj 

OJ    C- 


bJO  ^  C^ 

C  .*3  %    ' 


^tf    V 


B  ^o 

D  ^2    W 

o  8H 

VH 

a 


MISCELLANEOUS.  231 

FORMULA: 


FT— OT  X  C  =  percentage 
FT  =  final  temperature  =  209 
OT  =  original  temperature  =60 
C  =  constant  =  .  0864 

EXAMPLE: 


209  =  final  temperature 
60  =  original  temperature 

149  =  difference  of  temperature 
.  0864  =  column  constant 


596 
894 
1192 


12 .  8736  =  12  9/10  per  cent,  nearly 


PUMPS  AND  TANKS. 

The  efficiency  of  a  pump  varies  with  the  type,  size,  lift,  elevation, 
temperature  of  water  and  friction.  The  steam  pump  is  flexible  as 
regards  capacity,  a  few  revolutions  faster  or  slower  will  greatly 
increase  or  diminish  the  quantity  delivered,  the  maximum  efficiency 
depending  on  details  as  to  size  and  connection  and  locating  pump. 
Hot  water  cannot  be  lifted  by  suction,  as  its  vapor  destroys  the 
necessary  vacuum,  hence  the  necessity  to  have  the  hot  water  flow 
to  the  pump.  When  long  suction  pipes  are  used  it  will  be  necessary 
to  have  a  larger  size  than  with  shorter  distances,  this  to  allow  for 
friction  which  might  prevent  adequate  supply  to  pump.  Use  as  few 
elbows  and  sharp  bends  and  valves  as  possible;  avoid  traps  or  air 
pockets  in  pipe  ;  suction  pipes  should  be  absolutely  air  tight.  A 
vacuum  chamber  should  be  placed  on  the  opposite  side  of  the  pump 
from  where  suction  enters  and  a  foot  valve  will  be  found  advantage- 
ous and  desirable,  the  latter  if  its  location  is  such  that  it  can  be 
drained  when  necessary.  The  valve  insures  quick  starting  of  pump 
by  keeping  suction  pipe  filled  with  water.  A  priming  pipe  will  be 
convenient  when  chambers  are  to  be  filled  to  enable  pump  to  start 
quickly.  In  starting  a  pump  under  pressure  it  oftentimes  happens 
that  the  pump  will  not  discharge  the  water  while  the  pressure  is 


232  THE  BOILER. 

resting  on  the  discharge  valve,  for  the  reason  that  the  air  in  pump 
cylinders  is  not  discharged,  but  only  compressed  by  the  motion  of 
plungers,  then  it  is  necessary  to  expel  air  from  pump  and  suction 
pipe.  This  can  be  done  by  placing  a  check  valve  in  the  discharge 
pipe  near  the  pump  and  opening  an  air  vent  on  the  discharge  be- 
tween pump  and  check,  or  on  a  valve  chamber  on  top. 

A  relief  valve  is  desirable,  to  prevent  damage  which  might  occur 
by  obstruction  in  discharge  line,  thus  increasing  pressure  on  pump  in 
excess  of  that  which  pump  was  designed  for. 

Sometimes  a  pump  when  first  started  will  deliver  a  good  stream 
of  water,  which  gradually  diminishes  in  volume  until  it  stops  entirely. 
One  reason  for  this  is  leak  in  suction  pipes  or  stuffing  box  of  pump, 
or,  when  suction  primer  is  used,  in  the  hand  pump  stuffing 
box.  Another  reason  might  be  that  the*  pump  lowers  the  suction 
supply,  thus  increasing  the  lift  until  there  is  not  sufficient  speed 
for  the  elevation.  If  the  pump  works  indifferently,  delivering  a 
stream  obviously  too  small,  it  is  generally  because  the  pump  was 
not  properly  primed  and  some  air  remains  in  the  top  part  of  pump 
shell.  Unless  primed  by  steam  ejector  the  pet  cock  or  plug  found 
on  top  of  pump  shell  should  always  be  open  while  priming,  and  the 
pump  must  not  be  started  until  water  flows  out  of  same. 

A  pump  with  horizontal  top  discharge  and  short  length  of  dis- 
charge pipe  is  sometimes  difficult  to  start,  especially  if  suction  lift 
is  high,  owing  to  the  fact  that  the  water  is  thrown  out  of  the  pump 
shell  before  the  water  in  suction  pipe  has  got  fairly  started,  thus 
allowing  air  to  rush  back  into  the  pump.  If  the  pump  is  to  work 
under  this  condition  it  is  better  to  use  a  pump  with  a  vertical  dis- 
charge and  deliver  through  an  elbow,  or  else  lead  the  discharge  pipe 
upward  for  a  short  distance  so  as  to  keep  a  slight  pressure  or  head 
on  the  pump,  and  after  priming  as  high  as  possible  start  quickly. 

There  is  generally  nothing  gained  by  running  above  the  proper 
speed  required  for  a  given  elevation. 


MISCELLANEOUS.  233 

To  find  the  theoretical  horse  power  required  to  elevate  water, 
multiply  the  gallons  pumped  per  minute  by  the  head  in  feet  and  by 
8.33  (weight  of  one  gallon  of  water)  and  divide  product  by  33,000. 
This  will  be  only  approximate. 

LEGEND:  EXAMPLE: 

800  =  gallons  per  minute  800  gallons  per  minute 

20  =feet  elevation  20  =feet  elevation 

8.33  =  weight  of  one  gallon  of  water 

16000 
8 .  33  =  weight  of  one  gallon  of 

water 
48000 
48000 
128000 


33000)133280.000(4.038  H.  P.  required 
132000 


1280  00 
990  00 

290  000 
264  000 

26  000 


Ordinarily  pumps  will  elevate  water  50  to  60  feet,  and  if  specially 
built  in  regard  to  strength,  could  elevate  100  feet,  depending  on 
speed. 


THEORETICAL  STEAM  CONSUMPTION. 

AT  A  PISTON  TRAVEL  OF  100  FEET  PER  MINUTE. 

For  use  with  this  table,  the  effective  piston  travel  is  only  that 
portion  of  the  total  travel  during  which  the  steam  valve  is  open. 
Thus,  if  an  engine  is  running  400  feet  per  minute,  and  cutting  off 
at  T/2  stroke,  its  effective  travel  will  be  200  feet,  and  its  theoretical 
steam  consumption  will  be  200  divided  by  100  multiplied  by  the 
amount  given  in  the  table  for  its  cylinder  diameter  and  steam 


234 


THE  BOILER. 


pressure.     The  actual  consumption  exceeds  the  theoretical  by  25 
per  cent  to  50  per  cent. 


*o  ^ 

Q'lS 

11 

-L-  C 

INITIAL  STEAM  PRESSURE 

o.S 

=  ">> 

s? 

60 

70 

80 

90 

100 

110 

120 

130 

140    150 

go 

uS 

STEAM  CONSUMPTION  IN  POUNDS  PER  HOUR 

8 

34.9 

365 

410 

455 

500 

540 

585 

630 

670 

720 

760 

9 

44.3 

465 

507 

575 

630 

690 

740 

800 

855 

920 

964 

10 

54.5 

570 

640 

710 

780 

845 

915 

985 

1050 

1125 

1185 

11 

66 

690 

770 

860 

940 

1020 

1110 

1190 

1270 

1360 

1435 

12 

78.5 

820 

920 

1020 

1120 

1220 

1320 

1420 

1520 

1620 

1710 

14 

107 

1120 

1250 

1390 

1530 

1660 

1800 

1940 

2070 

2210 

2330 

16 

139.6 

1460 

1625 

1810 

2000 

2160 

2350 

2530 

2700 

2880 

3040 

18 

176.7 

1850 

2070 

2290 

2530 

2750 

2970 

3200 

3420 

3650 

3850 

20 

218.2 

2290 

2550 

2840 

3120 

3380 

3660 

3950 

4200 

4500 

4750 

22 

264 

2760 

3090 

3430 

3760 

4100 

4430 

4780 

5090 

5440 

5750 

24 

314 

3290 

3660 

4070 

4490 

4860 

5270 

5680 

6060 

6480 

6820 

26 

369 

3870 

4310 

4800 

5270 

5720 

6200 

6680 

7110 

7600 

8020 

28 

428 

4490 

5000 

5560 

6110 

6650 

7190 

7750 

8260 

8820 

9310 

30 

491 

5160 

5750 

6390 

7010 

7610 

8250 

8880 

9490 

10120 

10680 

EXAMPLE:  To  determine  the  steam  consumption  of  a  12  and 
18  X  12  X  18  Duplex  Compound  Pump :  Piston  speed  85  feet  per 
minute :  Initial  Steam  pressure  100  pounds. 

Since  the  pump  is  duplex  and  since  live  steam  enters  the  high 
pressure  cylinders  only,  the  theoretical  consumption  would  be  double 
that  of  a  single  12"  cylinder ;  or  at  100  feet  piston  speed,  1220  X  2  - 
2440  pounds  per  hour. 

Theoretical  consumption  at  85  feet  piston  speed,  2440  X  .85  = 
2074  pounds  per  hour. 

The  actual  steam  consumption  exceeds  the  theoretical  by  20  per 
cent  to  50  per  cent. 

The  mean  pressure  of  the  atmosphere  is  usually  estimated  at  14.7 
pounds  per  square  inch,  so  that  with  a  perfect  vacuum  it  will  sustain 
a  column  of  mercury  29.9  inches,  or  a  column  of  water  33.9  feet 
high  at  sea  level. 

To  determine  the  proportion  between  the  steam  and  the  pump 
cylinder,  multiply  the  given  area  of  the  pump  cylinder  by  the 
resistance  on  the  pump  in  pounds  per  square  inch,  and  divide  the 
product  by  the  available  pressure  of  steam  in  pounds  per  square 
inch.  The  product  equals  the  area  of  the  steam  cylinder.  To  this 


MISCELLANEOUS.  235 

must  be  added  an  extra  area  to  overcome  the  friction,  which  is 
usually  taken  at  25  per  cent. 

The  resistance  of  friction  in  the  flow  of  water  through  pipes  of 
uniform  diameter  is  independent  of  the  pressure  and  increase  directly 
as  the  length  and  the  square  of  the  velocity  of  the  flow,  and 
inversely  as  the  diameter  of  the  pipe.  With  wooden  pipes  the  fric- 
tion is  1.75  times  greater  than  in  metallic.  Doubling  the  diameter 
increases  the  capacity  four  times. 

To  determine  the  velocity  in  feet  per  minute  necessary  to  dis- 
charge a  given  volume  of  water  in  a  given  time,  multiply  the  number 
of  cubic  feet  of  water  by  144  and  divide  the  product  by  the  area 
of  the  pipe  in  inches. 

To  determine  the  area  of  a  required  pipe,  the  volume  and  velocity 
of  water  being  given,  mulptily  the  number  of  cubic  feet  of  water 
by  144  and  divide  the  product  by  the  velocity  in  feet  per  minute. 

To  find  the  diameter  of  pump  plungers  to  pump  a  given 
quantity  of  water  at  100  feet  piston  speed  per  minute,  divide  the 
number  of  gallons  by  4,  then  extract  the  square  root,  and  the  result 
will  be  the  diameter  in  inches  of  the  plungers. 

To  find  the  number  of  gallons  delivered  per  minute  by  a  single 
double-acting  pump  at  100  feet  piston  speed  per  minute,  square 
the  diameters  of  the  plungers,  then  multiply  by  4. 

The  area 'of  the  steam  piston,  multiplied  by  the  steam  pressure, 
gives  the  total  amount  of  pressure  that  can  be  exerted.  The  area 
of  the  water  piston,  multiplied  by  the  pressure  of  water  per  square 
inch,  gives  the  resistance.  A  margin  must  be  made  between  the 
power  and  resistance. 

CAPACITY  OF  PUMPS   AT   100  FEET   PISTON   SPEED. 

A  travel  of  100  feet  piston  speed  per  minute  is  considered  prac- 
tical and  is  accepted  as  standard  speed.  Slow  speed  for  boiler 
feeding  is  recommended.  No  set  rule  can  be  given  to  cover  all 
conditions.  In  Fire  Pumps,  where  the  largest  quantity  of  water  is 
required,  the  speed  may  exceed  200  feet  per  minute. 


236 


THE  BOILER. 


THEORETICAL   CAPACITY   OF    PUMPS   AT    100    FEET   SPEED    OF 
PISTON  OR  PLUNGER. 


Diameter 
of  Pump 
or  Plunger 
in  Inches 

U.  S.  GALLONS  PER 

Diameter 
of  Pump 
or  Plunger 
in  Inches 

U.  S.  GALLONS  PER 

Minute 

Hour 

24  Hours 

Minute 

Hour 

24  Hours 

1 

4.07 

244.7 

5875 

14% 

828 

49704 

1192896 

1% 

6.37 

382.5 

9180 

143/2 

858 

51468 

1235232 

1;L/ 

9.18 

550.8 

13219 

14% 

887 

53256 

1278144 

1% 

12.49 

749 

17992 

15 

918 

55070 

1321915 

2 

16.31 

979 

23500 

15% 

949 

56928 

1366272 

2% 

20.6 

1239 

28180 

980 

58800 

1411200 

25.5 

1530 

36720 

15% 

1012 

60720 

1457280 

2% 

30.8 

1851 

44424 

16 

1044 

62668 

1504046 

36.7 

2203 

52878 

16  M 

1077 

64638 

1551312 

3% 

43.1 

2586 

62064 

1110 

66642 

1599408 

49.9 

2998 

71971 

16% 

1144 

68676 

1648224 

3% 

57.3 

3442 

82619 

17 

1179 

70752 

1698048 

4 

65.2 

3916 

94002 

17% 

1214 

72840 

1748160 

4% 

73.7 

4422 

106128 

1249 

74964 

1799136 

82.6 

4957 

118971 

17% 

1285 

77124 

1850976 

4% 

92 

5523 

132552 

18 

1322 

79314 

1903550 

102 

6120 

146880 

18% 

1359 

81528 

1956672 

5M 

112 

6745 

161934 

1396 

83778 

2010672 

123 

7404 

177696 

18% 

1434 

86060 

2065449 

5% 

134 

8093 

194248 

19 

1473 

88368 

2120832 

6 

146 

8812 

211511 

19% 

1511 

90660 

2175840 

6M 

159 

9562 

229500 

19//> 

1552 

93120 

2234880 

63^ 

172 

10344 

248256 

19% 

1590 

95400 

2289600 

185 

11152 

267660 

20 

1632 

97920 

2350080 

7  4 

200 

11995 

287884 

20% 

1673 

100380 

2409120 

7% 

214 

12867 

308808 

20^ 

1714 

102840 

2468160 

229 

13769 

330478 

20% 

1756 

105396 

2529504 

7% 

245 

14700 

352300 

21 

1799 

107952 

2590848 

8 

261 

15667 

376011 

21% 

1842 

110538 

2652912 

8% 

277 

16660 

399852 

213^ 

1886 

113154 

2715696 

294 

17688 

424512 

21% 

1930 

115800 

2779200 

8% 

312 

18741 

449978 

22 

1974 

118482 

2843568 

9 

330 

19828 

475887 

22% 

2020 

121194 

2908656 

349 

20944 

502668 

22^ 

2065 

123924 

2974176 

91^ 

368 

22092 

530208 

22% 

2111 

126696 

3040704 

9% 

388 

23280 

558720 

23 

2158 

129492 

3107808 

10 

408 

24480 

587518 

23  % 

2205 

132324 

3175776 

10% 

428 

25716 

617184 

233^ 

2253 

135186 

3244464 

449 

26989 

647789 

23% 

2301 

138078 

3313872 

10% 

471 

28290 

678960 

24 

2349 

140958 

3382992 

11 

493  - 

29616 

710784 

24% 

2399 

143952 

3454848 

11% 

516 

30986 

743677 

243^ 

2449 

146958 

3526992 

539 

32374 

776993 

24% 

2499 

149952 

3598848 

11% 

564 

33795 

811080 

25 

2550 

152994 

3671856 

12 

587 

35251 

846046 

253^ 

2653 

159179 

3820300 

12% 

612 

36735 

881640 

26 

2758 

165484 

3971630 

637 

38250 

918000 

263^ 

2865 

171908 

4125800 

12% 

663 

39816 

955584 

27 

2974 

178457 

4282967 

13 

689 

41370 

992880 

273^ 

3085 

185130 

4443125 

13% 

716 

42972 

1031328 

28 

3199 

191922 

4606125 

743 

44610 

1070640 

28K 

3314 

198838 

4772118 

13% 

771 

46278 

1110672 

29 

3431 

205876 

4941028 

14 

799 

47980 

1151536 

30 

3672 

220320 

5287675 

For  practical  purposes,  deduct 
deliver  its  theoretical  capacity. 


10  per  cent,   as  no  pump   will 


MISCELLANEOUS. 


237 


FRICTION  Loss  IN  POUNDS  PRESSURE. 

For  each  100  feet  of   length,  in  different  size,  clean  iron  pipes,  discharging 
given  quantities  of  water  per  minute. 


SIZES  OF  PIPES— INSIDE  DIAMETER. 


3-S 

I 

i 

! 

1    i     i 

16  in. 

18  in. 

OS 

5 

10 
15 
20 
25 
30 
35 
40 
45 
50 
75 
100 
125 
150 
175 
200 
250 
300 
350 
400 
450 
500 
750 
1000 
1250 
1500 
1750 
2000 
2250 
2500 
3000 
3500 
4000 
4500 
5000 

fin. 

3.3 

13.0 
28.7 
50.4 
78.0 

1  in. 

0.84 
3.16 
6.98 
12.3 
19.0 
27.5 
37  0 

liin. 

0.31 
1.05 
2.38 
4.07 
6.40 
9.15 
19  4 

Hm. 

0.12 
0.47 
0.97 
1.66 
2.62 
3.75 
5  05 

2  in. 

6!i2 
'  6!i2 

oioi 

2^  in. 

3  in. 

4  in. 

6  in. 

Sin. 

10  in. 

12in. 

14  in. 

..,.. 

0.21 

1.10 

48.0 

16.1 
20  2 

6.52 

8  15 

1.60 

24.9 
56  1 

10.0 
22  4 

2.44 
5  32 

0.81 
1  80 

0.35 
0  74 

0.09 

39.0 

9.46 
14  9 

7.20 
4  89 

1.31 
1  99 

0.33 

0.05 





21.2 
28.1 
37.5 

7.0 
9.46 
12.47 
19.66 
28.06 

2.85 
3.85 
5.02 
7.76 
11.2 
15.2 
19  5 

0.69 

0.10 

1.22 
1.89 
2.66 
3.65 
4  73 

0.17 
0.26 
0.37 
0.50 
0  66 

'6!67 
0.09 
0.12 
0  16 

'6.03 
0.04 
0.05 
0  08 

6.6  i 

6'.02 



'.'.'.'.'. 

:  :  :  :  : 

'.'.'.'.'. 

..... 

'.  ...  '. 


25.0 
30.8 

6.0.1 
7.43 

0.81 
0.96 
2.21 
3.88 

0.20 
0.25 
0.53 
9.94 
1  46 

0.07 
0.09 
0.18 
0.32 
0  49 

0.03 
0.04 
0.08 
0.13 
0  20 

6.'6i7 
6.062 

6.009 
6.036 

6.005 
6.020 

2.09 

0.70 
0  95 

0.29 
0  38 

0.135 

0.071 

0.040 

1.23 

0.49 
0  63 

0.234 

0.123 

0.071 

...... 

::;:: 

0.77 
1.11 

0.362 
0.515 
0.697 
0.910 

0.188 
0.267 
0.365 
0.472 
0.593 
0.730 

0.107 
0.150 
0.204 
0.263 
0.333 
0.408 

;:;:: 

.  .  .'  .  '. 



i  

I  

238 


THE  BOILER. 


PH 

s 

03 
0) 

£ 


0* 


CN    O 


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r^  00  u->  00  t^  <N  ro  O  <N  00  00  CN £ 

PH 
i-H  i— I  rH  <NJ  <V)  T}- 

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C->  CO  10  CM  O  ^  Ch  ^1  00 g 

i? 

03 

00  :::::::::::::     £ 

^>00 ,„ 

g 

t^  (N  O  CN  00  00  <N 
rt-  cy>  O  fO  00  vO  1>» 

i— 1 1— i  ro  ^-  >-o  r^  c^ 
o  o  01  vo  o    •    • 

C<]  ro  •**•  vo  <T>     •      • 


MISCELLANEOUS. 
SIZES  FOR  BOILER  FEED  PUMPS. 


239 


Diameter  of 
Strain  Cylinder 

Diam.  of 
Water 
Cylinder 

Stroke 

Horse  Power 
Boilers 

Steam 
Pipe 

Exhaust 
Pipe 

Suction 
Pipe 

Discharge 
Pipe 

zy>" 

2M" 

4" 

30  to    40 

H" 

MT 

1" 

«" 

4^ 

2^ 

4 

80  to  100 

y?, 

M 

2 

1M 

5^ 

3^ 

5 

140  to  160 

H 

1M 

2^ 

1H 

When  long  suction  is  required  use  larger  suction  pipe.  Ordi- 
narily allowance  for  boiler  feeding  is  to  deliver  1  cubic  foot  or 
7y2  gallons  of  water  per  horse  power. 


240 


THE  BOILER. 


M 


OTS 

8  o 


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r£      W 

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o   w 


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WJH   o3 


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rOiJ^t^oO 
xo  ^-O  ^o  10  *o  VD  vo  vo  vo  vO 


rH  »^  rH  i—  t  O  O^  I>*  10  ro  »~H 
i-HC<irO'^->01^v£)t^oO<^ 


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MISCELLANEOUS. 


241 


.  <u 
^w    > 


-d  ^ 
c    o 

rt    >> 


ll 

bo  "to 
'     ^ 


CO 


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le 
el 

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CT   & 

CO      W 

w.  'd 

£,§ 


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1)    _C) 
C     4J 

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PH 


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CSJCOCNCNeNC^C^CNCSCSirorOrororO 


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£    - 


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xov^iOxr)Xoir>vr>vOvOO>OvO'OvO'sOvOvO. 


c 
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242 


THE  BOILER. 


MISCELLANEOUS. 


243 


Rule  to  find  pressure  of  water  head :     Multiply  constant  .434 
by  number  of  feet  of  head. 

EXAMPLE: 

.  434  =  constant 
45  =feet  head 


2170 
1736 

19. 530  ^pressure  or   19^   Ibs.   approxi- 
mately 


TANKS. 

Rule  to  find  capacity  of  round  tank :     Square  diameter  in  inches 
and  multiply  sum  by  .7854,  then  by  height  in  inches ;  divide  this 
product  by  231.     This  gives  capacity  in  gallons. 
FORMULA : 

D2x.7854xh 

—  =  capacity  of  round  tank 
231 
LEGEND: 

D  =  diameter  of  tank  =  60" 
h  =  height  of  tank  =60" 
231  cubic  inches  in  one  gallon 

EXAMPLE: 

60"  =  diameter  of  tank 
60 


3600  =  diameter  squared 
.7854 


14400 
18000 
28800 
25200 

2827.4400 

60  =  height 

231)  169646 . 4000  (734 .  4  gallons  capacity 
1617 


794 
693 

1016 
924 

924 
924 


244 


THE  BOILER. 


U.  S.  GALLONS  IN  ROUND  TANKS. 

For  1   Foot  in  Depth. 


Dia. 
of 
Tanks. 

1   No. 
U.  S. 
Gals. 

Cubic  Ft. 
and  Area 
in  sq.  ft 

Dia. 
of 
Tanks. 

No. 
U.  S. 
Gals. 

Cubic  Ft. 
ami  Area 
in  sq.  ft. 

Dia. 
of 
Tanks. 

No. 
U.  S. 
Gals. 

Cubic  Ft. 
and  Area 
in  sq.  ft. 

ft. 

in 

ft. 

in. 

ft. 

in. 

1 

5.87 

.785 

5 

8 

188.66 

25.22 

19 

2120.90 

283  53 

1 

1 

6.89 

.922 

5 

9 

194.25 

25.97 

19 

3 

2177.10 

291  .04 

1 

2 

8. 

1.069 

5 

10 

199.92 

26.73 

19 

6 

2234 

298  .  65 

1 

3 

9.18 

1.227 

5 

11 

205.67 

27.49 

19 

9 

2291.70 

306  .  25 

1 

4 

10.44 

1.396 

6 

211.51 

28.27 

20 

2350  10 

314.16 

1 

5 

11.79 

1  .  576 

6 

3 

229.50 

30  .  68 

20 

3 

2409  .  20 

322  '.  06 

1 

6 

13.22 

1.767 

6 

6 

248  .  23 

33.18 

20 

6 

2469.10 

330  .  06 

1 
1 

7 
8 

14.73 
16.32 

1.989 

2.182 

6 
7 

9 

267  .  69 

287  .  88 

35  .  78 

38.48 

20 
21 

9 

2529  .  60 
2591. 

338.16 
346  .  36 

1 

9 

17.99 

2.405 

7 

3 

308.81 

41.28 

21 

3 

2653. 

354  (}(*, 

1 
1 
2 
2 

2 

10 
11 

1 
2 

17.95 
21.58 
23.50 
25.50 

27.58 

2.460 
2.885 
3.142 
3.409 
3  .  687 

7 
7 
8 
8 
8 

6 
9 

3 

6 

330.48 
352  .  88 
376.01 
399  .  88 
424.48 

44.18 
47.17 
50.27 
53  .  46 
56.75 

21 
21 
22 
22 
22 

6 
9 

3 

6 

2715.80 
2779.30 
2843  .  60 
2908  .  60 
2974.30 

363.'  05 
371.54 
380  .  1  3 
388.82 
397.61 

2 

3 

29.74 

3.976 

8 

9 

449  .  82 

60.13 

22 

9 

3040  .  80 

406  .  49 

2 

4 

31.99 

4  .  276 

9 

475.89 

63.62 

23 

3108. 

415  48 

2 
2 

5 
6 

34.31 
36  .  72 

4.587 
4.909 

9 
9 

3 

6 

502  .  70 
530  .  24 

67.20 
70.88 

23 
23 

3 
6 

3179.90 
3244  60 

424  '56 
433  .  74 

2 

7 

39.21 

5.241 

9 

9 

558.51 

74.66 

23 

9 

3314. 

443'  01 

2 

8 

41  .78 

5.585 

10 

587  .  52 

78.54 

24 

3384  10 

452.39 

2 

9 

44.43 

5.940 

10 

3 

617.26 

82.52 

24 

3 

3455. 

461  .86 

2 

10 

47.16 

6  .  305 

10 

6 

640  .  74 

86.59 

24 

6 

3526  60 

471.44 

2 

11 

49.98 

6.681 

10 

9 

678  .  95 

90.76 

24 

9 

3598.90 

481  .11 

3 

52.88. 

7.609 

11 

710.90 

95.03 

25 

3672  . 

490.87 

3 

1 

55.86 

7.467 

11 

3 

743.58  1   99.40 

25 

3 

3745.80 

500  .  74 

3 

2 

58.92    7.876 

11 

6  |  766.99  1  103.87 

25 

6 

3820  .  30 

510  71 

3 

3 

62.06 

8.296 

11 

9 

811.14 

108  .  43 

25 

9  I  3895.60 

520.77 

3 

4 

65.28 

8.727 

12 

846  .  03 

113.10 

26 

3971.60 

530  .  93 

3 

5 

68.58 

9.168 

12 

3 

881.65 

117.86 

26 

3 

4048  .  40 

541.19 

3 

6 

71  .97 

9.261 

12 

6 

918. 

122.72 

26 

6 

4125.90 

551  .55 

3 

7 

75.44 

10.085 

12 

9 

955.09 

127.68 

26 

9 

4204.10 

562 

3 

8 

78.99 

10.559 

13 

992.91 

132.73 

27 

4283. 

572.66 

3 

9 

82.62 

11.045 

13 

3 

1031.50 

137.89 

27 

3 

4362.70 

583.21 

3 

10 

86.33 

11.541 

13 

6 

1070.80 

143.14 

27 

6 

4443  .  10 

593.96 

3 

11 

90.13 

12.048 

13 

9 

1110.80 

148.49 

27 

9 

4524.30 

604.81 

4 

94. 

12.566 

14 

1151.50 

153.94 

28 

4606  .  20 

615.75 

4 

1 

97.96 

13.095 

14 

3 

1193.0 

159.48 

28 

3 

4688.80 

626.80 

4 

2 

102. 

13.635 

14 

6 

1235.30 

165.13 

28 

6 

4772.10 

637.94 

4 

3 

106.12 

14.186 

14 

9 

1278.20 

170.87 

28 

9 

4856  .  20 

649.  18 

4 

4 

110.32 

14.748 

15 

1321.90 

176.71 

29 

4941. 

660  52 

4 

5 

114.61 

15.321 

15 

3 

1366.40 

182.65 

29 

3 

5026  .  60 

671.96 

4 

6 

118.97 

15.90 

15 

6 

1411.50 

188.69 

29 

6 

5112.90 

683  .  49 

4 

7 

123.42 

16.50 

15 

9 

1457.40 

194.83 

29 

9 

5199.90   695.13 

4 

8 

127.95 

17.10 

16 

1504.10 

201.06 

30 

5287.70  1  706.86 

4 

9 

132.56 

17.72 

16 

3 

1551.40 

207  .  39 

30 

3 

5376.20 

718.69 

4 

10 

137.25 

18.35 

16 

6 

1599.50 

213.82 

30 

6 

5465  .  40 

730  .  62 

4 

11 

142.02 

18.99 

16 

9 

1648.40 

220.35 

30 

9 

5555  .  40 

742  .  64 

5 

146.88 

19.63 

17 

1697.90 

226.98 

31 

5646.10 

754.77 

5 

1 

151.82 

20.29 

17 

3 

1748.20 

233.71 

31 

3 

5737.50 

766  .  99 

5 

2 

156.83 

20.97 

17 

6 

1799.30 

240.53 

31 

6 

5829  .  70 

779.31 

5 

3 

161.93 

21.65 

17 

9 

1851.10 

247.45 

31 

9 

5922.60 

791.73 

5 

4 

167.12 

22.34 

18 

1903.60 

254.47 

32 

6016.20 

804  .  25 

5 

5 

172.38 

23.04 

18 

3 

1956.80 

261.59 

32 

3 

6110.60 

816.86 

5 

6 

177.72 

23  .  76 

18    6 

2010.80 

268.80 

32 

6 

6205  .  70 

829  .  58 

5 

7   183.15 

24.48 

18    9   2065.50 

276.12 

32 

9 

6301.50 

842  .  39 

3iy2  Gallons  equals  1  Barrel. 

To  find  the  capacity  of  Tanks  greater  than  the  largest  given  in 
the  table,  look  in  the  table  for  a  Tank  of  one-half  of  the  given  size 
and  multiply  its  capacity  by  4,  or  one  of  one-third  its  size  and  mul- 
tiply its  capacity  by  9,  etc. 


MISCELLANEOUS. 


245 


STEEL  TANK   DIMENSIONS. 


Diameter, 
Feet. 

Height, 
Feet. 

Thickness, 
Shell, 
Inches. 

Thickness, 
Head, 
Inches. 

Size, 
Angle    Iron, 
Inches. 

Weight, 
Lbs. 

3 

2y2 

t 

A 

1^ 

300 

3 

3 

fk 

ji2 

385 

4 

3 

A 

A 

l/^ 

475 

4 

4 

3 

_3_ 

1  ^ 

585 

43^*? 

4 

^L 

^ 

1^ 

670 

4^/9 

41^ 

T^ 

~re 

1^ 

730 

5 

4^1 

TG 

M 

2 

885 

5 

5 

TS 

M 

2 

955 

sy> 

5 

rs 

M 

2 

1065 

5  12 

$y> 

JL- 

2 

1135 

6 

51^ 

/€ 

M 

2 

1600 

6 

6 

/€ 

/€ 

2 

1700 

7 

6 

M 

M 

2 

2100 

7 

7 

M 

M 

2 

2350 

8 

7 

/•€ 

2^ 

2800 

8 

o 

/€ 

M 

2^i 

3000 

9 

8 

M 

M 

2^ 

3730 

9 

9 

/4 

2V^ 

4060 

10 

9 

A 

tk 

2^ 

4965 

10 

9 

A 

A 

2J^ 

5400 

10 

10 

A 

A 

2X 

5850 

12 

10 

A 

JL 

2  Vi> 

7250 

12 

12         \            S 

A 

2^1 

8300 

246 


THE  BOILER. 


i-H  •»*  t     O  CO  CD 

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,-H  —  H  *-i  C^  <M  CS|  CO  CO  CO  -^  -^  ^  i 


as 


t>.  •»—  i 
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MISCELLANEOUS.  247 

Rule  to  find  capacity  of  a  square  tank :     Divide  cubic  inches  of 
tank  by  231.     The  sum  will  be  the  number  of  gallons. 

EXAMPLE: 

Tank  60"  X  60"  X  60" 

60"  width 
60"  long 

3600 

60=  height 


gallons  in  cubic  foot  231)216000  (  =935  gallons  capacity 
2079 


810 
693 

1170 
1155 

15 


Rule  to  find  weight  of  water  in  same  tank :  Multiply  the  number 
of  gallons  by  8.33  (this  is  weight  of  one  gallon  of  water).  This 
sum  will  be  weight  in  pounds. 

EXAMPLE: 

935  =  gallons 
8 . 33  =  weight  of  one  gallon  of  water 


28  05 
280   5 
7480 

7788 .  55  =  weight  of  water  in  pounds 


248  THE  BOILER. 

WATER. 

One  U.  S.  gallon  equals  231  cubic  inches. 
One  U.  S.  gallon  equals  .133  cubic  feet. 
One  U.  S.  gallon  equals  8.33  pounds. 
One  U.  S.  gallon  equals  .83  imperial  gallon. 


One  imperial  gallon  equals  277.274  cubic  inches. 

One  imperial  gallon  equals  .16  cubic  feet. 

One  imperial  gallon  equals  10  pounds. 

One  imperial  gallon  equals  1.2  U.  S.  gallon. 


One  cubic  inch  of  water  equals  .03607  pound. 

One  cubic  inch  of  water  equals  .003607  imperial  gallon. 

One  cubic  inch  of  water  equals  .004329  U.  S.  gallon. 


One  cubic  foot  of  water  equals  6.23  imperial  gallons. 

One  cubic  foot  of  water  equals  7.48  U.  S.  gallons. 

One  cubic  foot  of  water  equals  62.321  pounds. 

One  cubic  foot  of  water  equals  .028  ton. 


One  pound  of  water  equals  27.72  cubic  inches. 
One  pound  of  water  equals  .10  imperial  gallon. 
One  pound  of  water  equals  .12005  U.  S.  gallon. 


One  ton  of  water  equals  35.98  cubic  feet. 
One  ton  of  water  equals  224  imperial  gallons. 
One  ton  of  water  equals  268.8  U.  S.  gallons. 


A  column  of  water  1  foot  high  equals  .433  pounds  pressure 
per  square  inch. 

A  pressure  of  1  pound  per  square  inch  equals  2.31  feet  of  water 
in  height. 

A  pressure  of  1  ounce  per  square  inch  equals  .144  feet  of  water 
in  height. 


MISCELLANEOUS. 


249 


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CO      -00     •OS—'M      •  O  CO  OJ  •*  00  W 
!M      •  !M      •  IN  M  M      •  CO  CO  CO  •*  -*t  1*3 

•  •     -CO <3> TjH      -143      -COOOO5     •  -— i  M  O  C5  00  t^  rH  i!? 

•  •     •  i— i i-t 'M      •  *M      •  *M  ^)  M      •  CO  fO  M  CC  •*  **  iO  IO 

-                                                                                               ••C«-'3^eOMO5TjHO«O*iaC'<J<Oi>O--'l^MMOaOOO'NOOTt<00*tCO 
E  ^H  ,-<  ,-1  ,-H  ,-H  ,-!  ,-*  ^H -H  —  r^'N'N'N'N'M'M'MM'M'M'NMM...   ,    „    „ 

•  •  ~U  -  ^U-  M  00  M  00  M  00  M  p  M  p  M  p  ^_  ^_  rt|  Ti<  Tf  T*<  Tj|  CO  CD  CO  00  00 
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250  THE  BOILER. 

Rule  to  find  length  of  belt :  Add  together  the  diameter  in  inches 
of  the  two  pulleys ;  divide  this  by  2  and  multiply  the  quotient  by  con- 
stant 3^4  (3.25)  ;  to  this  add  twice  the  distance  in  inches  between  the 
centers  of  shaft ;  the  result  will  give  length  of  belt  approximately. 

FORMULA: 


/2D\ 

(  ~2~)  XC+  (2xd)  =  length  of  belt 


LEGEND: 

D  =  diameter  of  pulleys  =30" 
20" 

C=  constant  =3.25 
d  =  distance  between  shaft  centers  =  10'  =  120' 


EXAMPLE: 

30"     and 

20    =  pulley  diameters 

2)50 

25 
3  .  25  =  constant 

1  25 
5  0 
75 


twice  distance  81.25 

between  centers  of  shaft  =240. 


321.25"  =  length  of  belt 


THE    USE    OF    BELTING. 

The  ultimate  strength  of  a  single  belt  one  inch  in  width  and 
one-quarter  inch  thick  is  about  750  pounds,  but  from  the  weaken- 
ing effect  of  the  several  methods  of  joining,  the  ends  not  more 
than  200  pounds  .per  inch  in  width  should  be  depended  upon  for 
ultimate  strain. 

Belts  will  transmit  a  force  of  about  55  pounds  for  every  inch 
in  width,  and  taking  the  average  thickness  of  belts  at  one-sixth 
of  an  inch,  this  means  a  strain  of  330  pounds  per  square  inch  of 
section. 

The  horse  power  of  a  laced  belt  becomes  a  maximum  at  a  speed 
of  87.41  feet  per  second,  or  5,245  feet  per  minute,  or  considerably 
over  a  mile  a  minute. 


MISCELLANEOUS.  251 

One  good  method  for  lacing"  a  belt  is  to  punch  the  holes  in  two 
rows  and  zigzag,  thus  a  six-inch  belt  would  have  seven  holes, 
four  nearest  the  end.  The  first  row  should  be  about  three-quarters 
of  an  inch  from  the  end  of  the  belt  and  about  the  same  from  the 
sides.  On  the  larger  belts  the  distance  would  be  somewhat  in- 
creased. Begin  the  lacing  in  the  center  of  the  belt  and  lace  both 
ways;  keep  the  ends  of  the  belt  in  line  and  the  tension  on  both 
ends  of  the  lace  the  same.  The  lacing  should  not  be  crossed  on 
the  side  of  the  belt  that  runs  next  the  pulley,  so  that  the  lacing 
on  that  side  will  be  parallel  with  the  edges  of  the  belt,  while  on 
the  other  side  it  will  be  at  an  angle.  Loose  belts  can  be  run  on 
less  power  it  takes  to  drive  that  belt,  and  in  order  to  run  the 
belt  loose  it  must  be  in  good  order ;  so  taking  care  of  belts  means 
less  fuel  for  power  and  longer  life  to  the  belts. 

Do  not  use  any  belt  dressing  that  will  make  the  belt  stick  to 
the  pulley.  The  use  of  a  little  good  oil  occasionally,  such  as 
neat's-foot,  to  keep  the  leather  soft  and  pliable,  will  give  the  very 
best  results. 


RULES    FOR    PULLEY    SPEED    CALCULATION. 

Rule  to  find  size  of  a  pulley  for  a  main  line  shaft,  if  the  speed 
of  shaft  and  diameter  of  pulley  on  the  counter  shafts  are  given: 
Multiply  the  diameter  in  inches  of  pulley  on  counter  shafts  by 
speed  and  divide  by  the  revolution  of  the  main  shaft;  the  sum  will 
be  the  diameter  of  the  pulley. 

EXAMPLE: 

Main  shaft  150  revolutions  per  minute;  to  drive  a  15"  pulley  350  revo- 
lutions per  minute  what  will  be  the  diameter  of  pulley  on  main  shaft  ? 

15"  diameter  pulley  counter  shaft 
350  revolution  of  counter  shaft 

750 

45 

150)5250(35"   diameter  of  pulley  for  main 
450  line 

750 
750 


252  THE  BOILER. 

To  find  size  of  a  pulley  for  counter  shaft  when  revolutions  of 
pulley  on  main  shaft  are  given :  Multiply  diameter  in  inches  of 
driving  pulley  by  the  revolutions  of  the  main  shaft  and  divide 
by  the  speed  required  on  counter  line. 

EXAMPLE: 

35"  diameter  of  pulley  main  shaft 
150  revolution  main  shaft 


1750 
35 

revolution  counter  shaft  350)  5250  (15"  pulley  for  counter  line 

350 


1750 
1750 


To  find  speed  of  counter  shaft  when  revolutions  of  the  main 
shaft  and  size  of  pulleys  are  known : 

Multiply  the  revolutions  of  main  shaft  by  the  diameter  in  inches 
of  the  pulley  and  divide  by  the  diameter  in  inches  of  the  pulley 
on  counter  shaft. 

EXAMPLE: 

•>      -  V 

35"  pulley  main  shaft 
150  revolutions 


1750 
35 

diameter    pulley,  counter    shaft  15)5250  (350  revolution  of  counter  shaft 

45 

75 
75 


Slip  of  belt,  also  thickness  of  same,  will  vary  the  revolutions 
some. 


MISCELLANEOUS. 
HORSE   POWER  SHAFTING  TRANSMISSION 


253 


Diameter  of 
Shaft     in     Inches 

REVOLUTIONS  PER  MINUTE. 

100 

125 

150 

175 

200    |     225 

250 

300 

350 

400 

,8::::::::::::: 

HORSE  POWER. 

1.2 
2.4 
,      4.3 
6.7 
10.0 
14.3 
19.5 
26.0 
33.8 
43.0 
53.6 
65.9 
80.0 
113.9 
156.3 

1.4 
3.1 
5.3 
8.4 
12.5 
17.8 
24.4 
32.5 
42.2 
53.6 
67.0 
82.4 
100.0 
142.4 
195.3 

1.7 
3.7 
6.4 
10.1 
15.0 
21.4 
29.3 
39.0 
50.6 
64.4 
79.4 
97.9 
120.0 
170.8 
234.4 

2.1 
4.3 
7.4 
11.7 
17.5 
24.9 
34.1 
43.5 
59.1 
75.1 
93.8 
115.4 
140.0 
199.3 
273.4 

2.4 
4.9 
8.5 
13.4 
20.0 
28.5 
39.0 
52.0 
67.5 
85.8 
107.2 
121.8 
160.0 
227.8 
312.5 

2.6 
5.5 
9.5 
15.1 
22.5 
32.1 
44.1 
58.5 
75.9 
96.6 
120.1 
148.3 
180.0 
256.2 
351.5 

3.1 
6.1 
10.5 
16.7 
25.0 
35.6 
48.7 
65.0 
84.4 
107.3 
134.0 
164.8 
200.0 
284.7 
390.6 

3.6 
7.3 
12.7 
20.1 
30.0 
42.7 
58.5 
78.0 
101.3 
128.7 
158.8 
195.7 
240.0 
341.7 
468.7 

4.3 

8.5 
14.8 
23.4 
35.0 
49.8 
68.2 
87.0 
118.2 
150.3 
187.6 
230.7 
280  0 
398.6 
546.8 

5.0 
9.7 
16.9 
26.8 
40.0 
57.0 
78.0 
104.0 
135.0 
171.6 
214.4 
243.6 
320.0 
455.6 
625.0 

}jj  

2J-  • 

*>j  5. 

•  >  1  1 

4j|:  .::::::::::: 

The  following-  table  gives  the  maximum  permissable  distances 
between  bearings  of  continuous  shafts: 


Diameterof  shaft  in  inches 

Distance  between 
wrought  iron 

Bearings  in  feet 
steel 

1 

12.27 

12.61 

2 

15.46 

15.89 

3 

17.7 

18.19 

4 

19.48 

20.02 

5 

20.99 

21.57 

6 

22.3 

22.92 

7 

23.48 

24.13 

8 

24.55 

25.23 

9 

25.53 

26.24 

10 

26.4 

27.18 

The  length  of  a  bearing  is  usually  given  as  three  times  the 
diameter  of  the  shaft  in  inches.  The  distance  between  bearings 
are  also  given  as  three  times  diameter,  the  product  being  expressed 
in  feet. 

Rule  to  find  diameter  of  a  shaft.  Multiply  the  horse  power 
to  be  transmitted  by  the  constant  100  for  wrought  iron ;  divide 
the  product  by  the  number  of  revolutions  per  minute  and  extract 
the  cube  root  of  quotient ;  this  sum  will  give  safe  diameter  of  shaft- 
ing. For  steel  use  constant  62.5. 

Rule  to  find  diameter  of  shafts  as  second  movers,  transmitting 
power  through  long  lines.  Use  preceding  rule,  using  constant  50 
for  wrought  iron  and  31.5  for  steel. 


254  THE  BOILER. 

Rule  to  find  diameter  for  counter  shafting  well  supported  by 
bearings  at  short  distances.  Use  preceding  rules  with  constant 
33  for  wrought  iron  and  21  for  steel. 

Rule  to  find  horse  power  a  given  shaft  will  transmit.  Multiply 
the  cube  of  the  diameter  by  the  revolutions  per  minute  and  divide 
the  product  by  100. 

For  SECOND  MOVERS  —  Multiply  the  cube  of  the  diameter  by 
twice  the  revolutions  and  divide  the  product  by  100. 

For  THIRD  MOVERS  —  Multiply  the  cube  of  the  diameter  by 
three  times  the  revolutions  and  divide  by  100. 

Approximately  a  one  inch  shaft  will  transmit  at  100  revolutions 
1  horse  power  as  first  mover,  2  horse  power  as  second  mover,  and 
3  horse  power  as  third  mover,  the  power  transmitted  with  safety 
will  vary  in  proportion  as  to  the  speed  and  as  the  cube  of  the 
diameter. 


RULES  FOR  STEAM  BOILERS. 

See  that  water-level  has  not  fallen,  and  examine  joints  and 
seams  to  detect  leakage,  and  furnaces  for  evidence  of  bulging. 

Blow  through  water  gages ;  open  blow-off  cock  to  remove  sedi- 
ment.; try  safety  valve  to  insure  free  action;  raise  dampers  to  clear 
flues  of  explosive  gases ;  and  stir  up  fire,  heating  boiler  and  setting 
slowly. 

In  case  of  low  water,  immediately  cover  the  fires  with  ashes, 
or,  if  no  ashes  are  at  hand,  use  fresh  coal,  and  close  ash-pit  doors. 
Don't  turn  on  the  feed  under  any  circumstances,  nor  tamper  with 
nor  open  the  safety  valve.  Let  the  steam  outlets  remain  as  they 
are. 

Close  throttle  and  keep  closed  long  enough  to  show  true  level 
of  water.  If  that  level  is  sufficiently  high,  feeding  and  blowing 
will  usually  suffice  to  correct  the  evil.  In  case  of  violent  foaming, 
caused  by  dirty  water,  or  change  from  salt  to  fresh,  or  vice  versa, 
in  addition  to  the  action  above  stated,  check  draft  and  cover  fires 
with  fresh  coal. 

In  preparing  to  get  up  steam  after  boilers  have  been  open,  or 


MISCELLANEOUS.  255 

out  of  service,  great  care  should  be  exercised  in  making-  the  man 
and  hand-hole  joints.  Safety  valve  should  then  be  opened,  and 
blocked  open,  and  the  necessary  supply  of  water  run  in  or  pumped 
into  the  boilers  until  it  shows  at  second  guage  in  tubular  and 
locomotive  boilers ;  a  higher  level  is  advisable  in  vertical  tubulars 
as  a  protection  to  the  top  end  of  the  tubes.  After  this  is  done  fuel 
may  be  placed  upon  the  grate,  dampers  opened,  and  fires  started. 
If  chimney  or  stack  is  cold  and  does  not  draw  properly,  burn  some 
oily  waste  or  light  kindling  at  the  base.  Start  fires  in  ample  time 
so  it  will  not  be  necessary  to  force  them  unduly.  When  steam 
issues  from  the  safety  valve,  lower  it  carefully  to  its  seat  and  note 
pressure  and  action  of  steam  gauge. 

If  there  are  other  boilers  in  operation,  and  stop  valves  are  to 
be  opened  to  place  boilers  in  connection  with  others  on  a  steam 
pipe  line,  watch  those  recently  fired  up  until  pressure  is  up  to  that 
of  the  other  boilers  to  which  they  are  to  be  connected ;  and,  when 
that  pressure  is  attained  open  the  stop-valves  very  slowly  and  care- 
fully. 

Never  feed  cold  water  into  a  boiler  as  it  is  injurious  to  the 
plates  and  liable  to  spring  the  seams  and  cause  them  to  leak.  A 
good  feed  water  heater  should  be  used ;  they  not  only  save  early 
repairs  on  the  boiler  but  effect  a  great  saving  in  the  consumption 
of  coal. 

Boilers  should  be  blown  off,  a  little  at  least,  once  or  twice  a 
day,  and  the  water  should  be  entirely  blown  off  at  least  once  every 
two  weeks,  depending  on  the  nature  of  the  feed  water.  Never 
blow  out  a  boiler  while  it  is  too  hot  as  the  arch  plates,  flues  and 
braces  retain  heat  enough  to  bake  the  deposits  of  mud  into  a  hard 
scale  that  becomes  firmly  attached  to  their  surface.  With  the  walls 
and  arches  too  hot  while  blowing  off,  the  plates  are  liable  to  injury. 
Always  allow  the  setting  to  cool  down  before  emptying  completely 
as  the  scale  and  mud  will  then  be  quite  soft  and  can  easily  be 
washed  out  with  a  hose. 

If  necessary  to  blow  down,  allow  the  boilers  to  become  cool 
before  filling  again.  Cold  water  pumped  into  hot  boilers  is  very 
injurious  from  sudden  contraction. 

Care  should  be  taken  that  no  water  comes  in  contact  with  the 
exterior  of  the  boiler,  either  from  leaky  joints  or  other  causes. 


256  THE  BOILER. 

In  tubular  boilers  the  hand  holes  should  be  often  opened,  and 
all  deposits  removed,  and  fire-plates  carefully  cleaned. 

Keep  the  boiler  clean  internally  and  externally  and  thoroughly 
examine  plates  and  seams  at  frequent  intervals,  especially  those  in 
contact  with  setting  or  exposed  to  direct  action  of  fire. 

Always  raise  steam  slowly  and  never  light  fire  until  water  shows 
in  gauge  glasses.  Keep  furnace  walls  in  good  condition  and  well 
pointed  up.  Allow  boiler  and  brick  work  to  cool  before  emptying 
boiler.  Prevent  oil  and  greasy  matter  from  entering  boiler,  as 
same  lead  to  serious  inefficiency  and  to  dangerous  heating  of  plates. 

Mud  drums  should  be  given  careful  attention  and  cleaned  and 
inspected  regularly  just  the  same  as  the  boiler. 

Try  the  safety  valves  cautiously  and  often,  as  they  are  liable 
to  become  fast  in  their  seats  and  useless  for  the  purpose  intended. 
If  the  valve  is  of  the  lever  type,  do  not  load  it  with  additional 
weights.  The  safety  valve  is  set  to  blow  off  at  a  certain  pressure 
and  should  blow  off  when  the  steam  gauge  registers  this  pressure ; 
if  it  does  not,  one  or  the  other  is  wrong  and  should  be  corrected. 

When  a  blister  appears  there  must  be  no  delay  in  having  it 
carefully  examined,  and  trimmed  or  patched,  as  the  case  may 
require. 

Particular  care  should  be  taken  to  keep  sheets  and  parts  of 
boilers  exposed  to  the  fire  perfectly  clean ;  also  all  tubes,  flues 
and  connections  well  swept.  This  is  particularly  necessary  where 
wood  or  soft  coal  is  used  for  fuel. 

See  that  proper  water-level  is  maintained.     Keep  water  gauge 
classes  clean  and  passages  clear,  by  trying  gauges  frequently. 
(Lack  of  proper  attention  to  water  gauges  leads  to  more  accidents 
than  any  other  cause.) 

Maintain  a  fire  of  even  thickness,  free  from  holes  and  clear  of 
ashes  and  clinkers.  (The  proper  thickness  of  fire  increases  with 
the  hardness  and  size  of  coal  and  with  the  strength  of  draft.) 
Regulate  fire  and  draft  and  feed  to  meet  demands  for  steam,  keep- 
ing water  level  constant  to  avoid  priming  or  burning  of  plates. 
Ash  pits  are  to  be  kept  clear  to  avoid  burning  grate  bars  and  to 
prevent  loss  of  draft  and  efficiency. 

Never  attempt  to  stop  a  leak  or  tighten  a  joint  when  boiler  is 


MISCELLANEOUS.  257 

under  high  pressure.  Never  cut  in  a  boiler  with  a  battery  until 
its  pressure  is  equal  to  that  of  the  battery. 

Before  banking  fires  run  water  to  proper  level,  which  note,  and 
see  that  the  steam  pipe  drains  are  open  and  in  working  order. 

Water  in  ash  pit  has  an  effect  of  clinkering,  and  this  varies 
with  the  amount  of  sulphur  and  iron  pyrites  and  ash  in  fuel,  thus 
choking  up  air  spaces  in  grate  effecting  the  life  of  same.  Again 
the  moisture  mixing  with  sulphur  has  the  corrosive  effect  on  boiler 
and  "tubes;  it  also  has  a  cooling  effect  which  detracts  from  com- 
bustion, and  volatile  gases  escape  unconsumed. 


NOTES. 

Slight  leakage  at  joints  causes  grooving. 

Covering  of  boiler  and  steam  pipes  saves  fuel  and  increases 
efficiency. 

A  boiler  showing  pulsations  of  engine  gives  evidence  of  being 
too  small  for  duty. 

Fly  wheels  should  not  have  a  greater  speed  than  one  mile  per 
minute  to  be  safe. 

Globe  valves  should  always  be  so  placed  in  steam  pipes  that 
their  stems  are  nearly  horizontal. 

Stack  should  drain  inside  —  for  reasons  —  appearance  — as 
stacks  are  in  use,  most  of  the  time,  the  advantage  of  having  drain- 
age outside  is  not  to  be  weighed  with  the  advantage  of  draining 
inside  and  appearance. 


258 


THE  BOILER. 
KNOTS  AND  MILES. 


Knts 

Miles 

Knts 

Miles 

Knts 

Miles 

Knts 

Miles 

Knts 

Miles 

1.00 

1.1515 

6.00 

6.9091 

11.00 

12.6667 

16.00 

18.4242 

21.00 

24.1818 

1.25 

1.4394 

6.25 

7.1970 

11.25 

12.9545 

16.25 

18.7121 

21.25 

24.4697 

1.50 

1.7273 

6.50 

7.4848 

11.50 

13.2424 

16.50 

19.0000 

21.50 

24.7576 

1.75 

2.0152 

6.75 

7.7727 

11.75 

13.5303 

16.75 

19.2879 

21.75 

25.0455 

2.00 

2.3030 

7.00 

8.0606 

12.00 

13.8182 

17.00 

19.5758 

22.00 

25.3333 

2.25 

2.5909 

7.25 

8.3485 

12.25 

14.1061 

17.25 

19.8636 

22.25 

25.6212 

2.50 

2.8788 

7.50 

8.6364 

12.50 

14.3939 

17.50 

20.1515 

22.50 

25.9091 

2.75 

3.1667 

7.75 

8.9242 

12.75 

14.6818 

17.75 

20.4394 

22.75 

26.1970 

3.00 

3.4545 

8.00 

9.2121 

13.00 

14.9697 

18.00 

20.7273 

23.00 

26.4848 

3-25 

3.7424 

8.25 

9.5000 

13.25 

15.2576 

18.25 

21.0152 

23.25 

26.7727 

3.50 

4.0303 

8.50 

9.7879 

13.50 

15.5455 

18.50 

21.3030 

23.50 

27.0606 

3.75 

4.3182 

8.75 

10.0758 

13.75 

15.8333 

18.75 

21.5909 

23.75 

27.3485 

4.00 

4.6061 

9.00 

10.3636 

14.00 

16.1212 

19.00 

21.8788 

24.00 

27.6364 

4.25 

4.8939 

9.25 

10.6515 

14.25 

16.4091 

19.25 

22.1667 

24.25 

27.9242 

4.50 

5.1818 

9.50 

10.9394 

14.50 

16.6970 

19.50 

22.4545 

24.50 

28.2121 

4.75 

5.4697 

9.75 

11.2273 

14.75 

16.9848 

19.75 

22.7424 

24.75 

28.5000 

5.00 

5.7576 

10.00 

11.5152 

15.00 

17.2727 

20.00 

23.0303 

25.00 

28.7879 

5.25 

6.0455 

10.25 

11.8030 

15.25 

17.5606 

20.25 

23.3182 

25.25 

29.0758 

5.50 

6.3333 

10.50 

12.0909 

15.50 

17.8485 

20.50 

23.6061 

25.50 

29.3636 

5.75 

6.6212 

10.75 

12.3788 

15.75 

18.1364 

20.75 

23.8939 

25.75 

29.6515 

TABLE  'SHOWING    KNOTS    REDUCED    TO    MILES. 

A  nautical  mile  or  knot  is  6,080.27  feet. 


CONTENTS 


CHAPTER  I.  PAGE 

MATERIALS  5 


CHAPTER  II. 
SELECTION  OF  BOILER        .  ...  18 

CHAPTER  III. 
BOILER  CONSTRUCTION        ...         .         .         -.         .  35 

CHAPTER  IV. 
BRACES  AND  REINFORCEMENT     .         .         .         .         .  .       .  69 

CHAPTER  V. 
FURNACES,   FLUES  AND  U.  S.   RULES.       •  /-       .         ...      106 

CHAPTER  VI. 
LAP  JOINT  RULES       .         .         .         .         .         .         .         .         126 

CHAPTER  VII. 
BUTT  JOINT  RULES     .         .         .         .         .         .         .         .154 

CHAPTER  VIII. 
THE  STEAM  BOILER  ........         175 

CHAPTER  IX. 
INSPECTIONS        .........         200 

CHAPTER  X. 
MISCELLANEOUS 223 

259 


INDEX 


Adamson  furnace  rules ; 120  to  122,  125 

Angle  irons,   sizes  and  weights,  table 55 

B 

Belting,  tables  and  rules 249  to  251 

Boilers,  construction 35  to     67 

"        designing 6,  16,     17 

".       U.  S.  Government  requirements 218 

"         selection 18 

"        hot  water,  rules  and  tables 159 

"        standard  measurements 181,  182 

heating,  low  pressure 198 

"        verticle,  specifications,  tables 197 

weights,  table  of 185 

"        water  tube  or  coil,  rules 221,  222 

Boiler  room,  rules  and  notes 254  to  257 

Braces,  measurements  and  weights „ 52 

"        number  for  standard  boilers,  table 53 

"        number,  and  rule  to  find 90 

rods,  rule  to  find  working  pressures 94 

"        and  bracing,   material 69.     70 

socket  bolts,  rules  to  find  pressure 125 

formed 94 

Butt  Joints 154  to  172 

Brown  Furnaces 117 

c 

Channel  steel,  size  and  weight,  table 56 

Chimneys  and  stacks,  rules  and  tables 189  to  196 

Circles,  rules  for  calculations,  segments 20  to  23,  88,  89 

"        tables  of  areas  and  circumference 24,  25 

Cones,   rules    118,  119 

Collapsing  pressures,  furnaces,  rule  to  find 113  to  116,  123.  124,  126 

Curved  surfaces,  rule 95 

260 


INDEX.  261 


Dome  plate 48 

Drills,  table  of  sizes 61 

*Drums  and  Heads,  U.  S.  Government  requirements 220 

E 

Engines,  power 18,  19,  31 

"        types,   efficiencies,   table 20 

Engineers,  marine,  classification 208  to  212 

qualifications   and   duties 208  to  212 

F 

Feed  water,  heaters  and  heating 223  to  229 

"        admission 217 

heating,  tables  and  rules 230.  231 

Flanges,  diameters,  sizes  for  pipes 58 

Furnaces 105 

plain,  rules  and  tables 108  to  112,  120 

Morrison,    rules 113,    114,  121 

"        U.  S.  Government,  rules  and  tables 108  to  112 

Purvis,    rules 117,  121 

"        verticle,    rules 121 

"        Leeds   Suspension,   rules 116 

Brown , 117,  121 

Flues  and  furnaces 106,  108,  109 

plain,  rules .  .110  to  122 


G 

Gauge  cocks  and  water  glass 219 

Girders,  rules .99,  103 

Grate  surface,  rules  and  tables - 183,  184 


H 

Heads,  flat 85 

cast  iron,   rule 88 

"       convex,  rule 86 

"       concaved 87 

boiler,  diameter  and  weights,  table , 40  to  42 

Heating  surface,   ratios,  tables 183.  198 

"        surface,  rule  to  find 50 

Horse  power,  tables  and  rules 26,  27,  28,  181,  182 

Hydrostatic  test .  220 


262  THE  BOILER. 


I  beams,  sizes  and  weights 55 

Iron,  cast,  composition,  tables  of  properties 7    217 

wrought g 

cast,  balls,  diameter  and  weight,  table 55 

Inspections,  U.  S.  Government  rules 106  to  122,  219 

of  boilers 212  to  222 

J 

Joints,  lap,  single  riveted,  rules 127  to  137 

lap,  single  riveted,  table  of  efficiencies 137 

lap,  double  riveted,  rules . .  138  to  149 

lap,  double  riveted,  table  of  efficiencies 149 

lap,  triple  riveted,  rules 150  to  153 

lap,  triple  riveted,  table  of  efficiencies 153 

butt,  double  strapped,  double  riveted,  rules 154  to  159 

butt,  double  strapped,  double  riveted,  table  of  efficiencies 159 

butt,  double  strapped,  triple  riveted,  rules 160  to  168 

butt,  double  strapped,  triple  riveted,  table  of  efficiencies 164 

butt,  double  strapped,  quadruple  riveted 169  to  174 

butt,  double  strapped,  quadruple  riveted,  table  of  efficiencies 172 

K 

Knots   and   miles 258 

L 

Lap  joints 127  to  153 

M 

Materials . .  5  to  16 

U.  S.  Govt.  inspection,  selection,  tests 11.  106,  107 

Metals,  weights  and  table  of ' 53  to  55 

Morrison  furnace 113  to  121 

N 

Notes  on  boiler  room,  rules,  etc ; 254  to  257 

P 

Pipe,  steam,  heating,  radiation,  table 198,  221 

expansion  and  radiation,  table 58 

and  piping 56 

steam,  gas,  water,  dimensions,  table 59 


INDEX.  263 

Pipe,    rules  to  find  thickness  of 57 

friction  loss  in  discharge,  table 237 

"       discharge  at  nozzle,  table 240 

Plates,  steel,  rules  and  tables 6,  9,  10,  11,  43  to  48 

Pressures,  U.  S.  Govt.  rules,  shells 175 

U.  S.  Govt.  tables 176  to  180 

water  heads,  tables  and  rules ' 241,  242,  243 

U.   S.   Govt.   requirements 222 

Pump,  rules 231 

tables,  notes 234,  235 

"       capacities 236 

piping  table 237 

"       elevation    of    water 238 

"       feed,   size,    table 239 

Pulleys,  rules  for  calculations 251,  252 

Purvis  Furnace    251,  252 


R 

Reinforcement  of  openings,  rules 103  to  105 

Rivets  and  Riveting,  table 1 36  to  39 

*'  shearing  strength  of 38,  39,  68 

Rods,  braces,  rules 94 

Rules,  for  calculating  circles 20,  88 

"       mensuration 20,  23 


S 

Safety  valve,  rules  and  tables 200  to  207 

Settings,  boiler 185,  186 

"        measurements 186,  187 

materials  for 188,  189 

Shafting,  rules  and  tables 253,  254 

Shearing  strength  of  rivets 38,  39,  68 

Socket  bolt  rules 125 

Steam  boiler  notes 254  to  257 

notes 28,  32 

pressures,  temperature  and  tables 29 

Steel,  flat,  weight  per  foot,  table 62,  63 

round,  square,  weights,  table 61,  62 

"      cast 217 

Stay  bolts,  sizes  and  threads  of  same 60 

"     bolts,  strain,  areas,  bracing  of 71,  84 


264  THE  BOILER. 


Tables,   decimals,   circumferences,    areas 24  to  26 

pressures  and  temperature 29 

"        weights  and  size  of  boiler  heads 40 

I  beams 56 

"        sizes,  threads,  flanges 58 

flat  steel,  sizes  and  weights 63 

"        metals,  weights 63,  64 

Birmingham  and  U.  S.  standards,  gauges 53,  54,  63,  64 

"        rivets 37 

shearing  strength  of  rivets 38,  39 

circumference,  areas  and  decimals 24,  25.  26 

areas   of  circular  arcs 91  to  93 

horse   power   boilers 176  to  181 

weights  of  boilers 185 

"        chimneys  and  stacks 191,  195 

for   safety  valves 202,  203 

Tanks,  capacities,  tables  and  rules 244  to  247 

Taps  and  drills 61,  62 

Testing,  boiler  plate,  drilling 219,  222 

Thermometer,    rules   and  tables 32,  33,  34 

Tube,  rules  and  tables,  standard  sizes 49  to  51 

plates,  rule  to  find  pressures 96  to  98 

4<      plates,  thickness 97 

plates,  compressive  strain 98,  101,  124 


U 

U.  S.  Government  rules,  tables,  pressures 175  to  180 

V 

Verticle  boiler,  table  of  specifications 197 

w 

Water  tube  and  coil  boiler  requirements 221,  222 

pressure  tables  and  rules 241,  242,  243 

"       measurement,  notes 248 


:BR^ 

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NOV    30  1932 
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JAN  23  1944 
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MJT0.01SC 


LD  21-50m-8,*32 


1 95030 


, 


ij  i  i         i  !  1        1 
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1 


